This sentence would be unacceptable in British English:
I fed the kids already.
Ich bin gerade geschwommen, als ich den Hai gesehen habe.
I was swimming when I saw the shark.
… French with their parents until they started school, when they switched to German.
… no matter where he was or what he … (do) the previous day.
had been doing
His first thought was the realization that he … (still wear) shirt and trousers, …
was still wearing
He … (go) to his club for supper, …
had gone
He … (have to) pay more attention to his diet in future.
would have to
So Zircon, the organisation which … (seek) to control the free western world, was back in business?
sought
Its founder, Leon B., was dead. Pym knew this, he personally … (arrange) his death.
had arranged
But who controlled Zircon now? Doubtless Z … (tell) him upon his arrival.
would tell
Last changeda year ago