Don’t worry if you don’t understand everything, the teacher will ______ the main points at the end.

3She stared at the painting, wondering where she      it.

I tried phoning her office, but I couldn’t _______.

His sister left home in 1998, and _______since.

A．had not been heard of

B．has not been heard of

C．had not heard of

D．has not heard of

It's an either-or situation - we can buy a new car this year or we can go on holiday but we can’t do     .

At our factory there are a few machines similar to _______ described in this magazine.

Half of _____surveyed in 16 countries say they go first to their closest friend to share their deepest wishes and darkest fears.

Recycling is one way to protect the environment; reusing is ______. 

The traffic on the main streets has a longer green signal than _______ on the small ones.

Those who smoke heavily should remind ________ of health, the bad smell and the feelings of other
people.