-----When will they come back? 　　-----I _____ don’t know.

In the bubble years, lending standards slipped ______,allowing   many people to put far too much of their income into paying for their housing.

We should unite, for no country _____can solve the problem of the pig flu.

My uncle lost his ID card yesterday. ______, a boy found it and gave it back to him last night. 

A new study of HIV-infected people in Haiti indicates that starｔing treatment early could save many patients who might _______ die of AIDS.