The short answer is that no, they do not mean the same thing.
The first with an inflection of the progressive construction be playing is a simple statement of the evidentiary future, but the second with an inflection of will play is a statement of a future that the speaker insists must come to pass.
Probabilities vs Demands
When someone says:
I will not ...
She may have reasoned that it would have been against her own economic self interest to disclose the worst case scenario.
This sentence has an embedded content clause marked by the subordinator that:
it would have been against her own economic self interest to disclose the worst case scenario,
This content clause has an extraposed subject. Here, dummy it ...
Last time I counted them, I found two hundred and seventy-seven English conditionals. There are of course others.
See this answer for details.
I: If he will jump, you will not have to.
II: If he will jump, he can win.
III: If he will jump, he may win.
IV: If he will jump, you must follow.
V: If he will jump, you ...
The example that you identify as correct expresses a general of habitual state: John likes ice cream. This is not something John did yesterday, or at any specific time, it expresses a general truth about John's likings.
This is one of the ways in which the simple present is used, and when used in that way, it can be used in a subordinate clause following a ...
The difference between the first and second sentences are that the first uses the mandative subjunctive go and the second uses the past indicative went. You can see this by considering the sentences:
He wanted to go back to Kazakhstan, so I suggested he go with me.
He wanted to go back to Kazakhstan, so I suggested he went with me.
He wanted to go back to ...
You asked quite a few questions. Here is an attempt at providing answers to a portion of them.
1. Is this something new or something old? Has it always worked this way in English even before the Conquest, or did we get it grafted onto us by the Norman French?
I am surprised you passed without comment OED's sense 1a(b) [with object clause with may or (...
There is no rule which says that all tenses in a statement have to be the same. Please believe that.
In this latest question, I asked puts your action in the past. The next verb defines when on the timeline its event lies. If you used lived, it puts the timestamp of living at the same point as your question; lives implies that the residence is still going on....
There are two issues: Tense agreement and construction of a conditional.
The first sentence is not correct because there is not tense agreement between the verbs “did...change” (past tense) and “have” (present).
A second reason is that the construction “How...if...” calls for a conditional, so “would” is a better auxiliary than “did.”
This is reported speech, where we backshift tenses. Backshifting happens when a verb tense is shifted back to a past form in reported speech.
What was said by John: "I am hungry." In reported speech, we see "John said that he was hungry."
In your example "I told him I wasn’t playing soccer anymore", what was actually said was &...
There is a valid literary technique that will subtly shift from past to present but it is much safer to pick one tense and stick with it.
An example of this device, which I copied from About.com's page on the subject:
Off the road there was what appeared to be a reviewing stand, and I sat there for a few moments, taking in the museum and the cold blue ...
From English Club (slightly modified) :
In reported speech:
He said: "I feel sad." becomes He said that he felt sad.
John said (that) he was hungry. ... John's original words: "I am hungry."
[As is seen, w]e sometimes change the tense of the reported clause
by moving it back one tense. For example, present simple goes back one
Your intuition is right. There is no grammatical requirement of tense agreement between the main clause and its dependent clause. In each clause, you simply choose the tense which conveys the intended meaning. So in your example, "has" would be used if the system now has the potential. "Had" would be used if the system had the potential but does not now.
Simply because He was believed to have been in debt would refer to a time before the time when the thinking was going on: they believed (a year ago) that he had been (two years ago) in debt. (This is sometimes called the pluperfect, to distinguish it from the normal past tense.) Strictly speaking, there is no implication one way or the other whether he had ...
This a narrative form in present continuous. The author is putting us there, in the action, and we are experiencing the action with the actor, in real time. Even with that, though, there is still the concept of past actions, so it is reasonable to say that the doorbell has rung three times.
When you change "is standing" to "stood", you are being ...
As RoryAlsop notes, you have a problem with agreement in number between "ideas" and "is/was". But ignoring that and getting to your question:
All are valid. They technically mean slightly different things.
"He agrees is" means that he agrees in the present. "He agreed is" means that at some time in the past he agreed that this was a solution in the on-...
I don't think any of those quite work, but not because of tense. Try this:
I shared an idea with Jon, which he agreed was a good solution for the problem we are facing.
So we have "shared" and "agreed was" matching tense, and we have a singular idea.
Yes, your sentence is grammatically correct:
My grandma believed that the sun revolves around the earth.
But I disagree that "universal truths are always in present tense". On the contrary, it is perfectly fine to say:
My grandma did not believe that the earth revolved around the sun.
preserving the proper coordination of tenses.
An answer in this site says (inter alia)
The praeterite is traditionally called “the past tense” form but this is only one of its functions. The praeterite can be used to express the certain past (indicative) or the uncertain present (subjunctive). Like the unmarked certain form, absent of other time-marking or mood-marking, the default for the praeterite ...
I asked if he hunts bears. Yes, he hunts bears for a living. He is a bear hunter. He kills bears.
Yesterday, I asked if he killed the bear lying on the road. No, he has not killed any bear since the hunting season has closed. Someone else killed the bear illegally.
He speaks French. Last week he spoke French to his mother. He has not spoken French since ...
The use of present perfect has caused indicates that the event happened in the recent past and its effects are still current.
Imagine a meeting within the first hour of the earthquake:
We held a meeting in Washington.
The president learned that the earthquake has caused havoc all across the country.
The National Guard was mobilised.
All of those ...
There was a rumour (at the meeting I just attended) that Brokenshire is (currently) in debt.
That would seem to me to be a perfectly valid construction.
But Six moths ago there was a rumour circulating that Brokenshire was (then) in debt.
This is entirely a question of which tenses sound right in the circumstances. But they do not have to match, for ...
In this context, the idiom "it is over" or "it is finished" is referring to a relationship. Only if the relationship were to change again (perhaps Bridget and John started dating again) would the status of the relationship change. At that point, someone might say "it was finished", since the state has changed.
"It is finished" is the correct ...
I am a US speaker—my native dialect is southern—and Mr. Corbyn employs this construction in the only way familiar to me, with the verb in its past form:
It's time we went home.
It's time we were going.
I cannot recall ever encountering this with a present-form verb, although a version with a marked infinitive is common:
It's time to go ...