I think your questions sounded too i just now. You can ask by using "could" instead of "can".

I have collected some s of the 70th anniversary of the victory of the Anti-Japanese War.

Many visitors are f by West Lake in Hangzhou. It's well worth visiting.

This morning the traffic was u so I was not late for work like yesterday.

Tom r to school because he was late for class.

Yesterday she m a letter to her sister at the post office after putting a stamp on the envelope (信封).

If students can't pass all the c , they can't graduate.

We shouldn't ask a stranger for help too d . It's impolite if we don't use some words to lead into the conversation.

When problems were solved, the broken machine could work n in the end.

Without knowing her a , the postman couldn't send her the letter.