(2013·高考重庆卷)—What are  you doing this Saturday?—I’m not sure，but I________go to  the Rolling Stones concert.

We should spend as much time as we _______ over our lessons.

I got close enough to hear them speaking Chinese, and I said “Ni Hao ” just as I ____ do in China.

It is usually warm in my hometown in March, but it ____be rather cold sometimes.

The lady in the sitting room           be over sixty. She looks so young.