both vs by the time

[hela]

Dear Teachers,

1) Are Before and By the time synonyms? Are they interchangeable? If not, what is the difference between them?


2) Are the following sentences correct? What do they mean exactly?

a) It is strange that he should have left so early.

b) I wish I understood what they are saying.
c) I wish I understood what they were saying.

Thank you for your help.
Hela

[Casiopea]

1) Are Before and By the time synonyms? Are they interchangeable? If not, what is the difference between them?

They share a similar meaning, yet they also mean different things. 'before' means, earlier than, whereas 'by the time' means, earlier than or no later than, for example

A. I'll be home before you start dinner at 6pm.
(earlier than 6pm, maybe 5:30, 5:45, etc.)

B. I'll be home by the time you start dinner at 6 o'clock.
(ealier than 6pm or at 6pm)

2) Are the following sentences correct? What do they mean exactly?

a) It is strange that he should have left so early.
b) I wish I understood what they are saying.
c) I wish I understood what they were saying.

a) and b) are not acceptable in my dialect, so, sorry, I can't help you out there. As for c), it means, I don't understand what they are saying, but I wish I did (understand what they were saying).

:D