It was not until the subprime loan crisis (次贷危机) ____ great damage to the American financial system that Americans ____ the severity of the situation.

16 I have never heard such a beautiful song _____

I’m sorry I didn’t make it to your party last night.—_______, I know you’re busy these days.

Last night Dad and Mum didn’t come backhome ________ I finished my homework.

What do you think of the film Avatar?—It________be better.I even want to see it twice