We must behave ____ at a formal table

dioxide, which makes a ______ between us andthe sun, prevents heat from getting out of the atmosphere easily, so the earthis becoming warmer

I called you at half past nine this morning, but there was no answer.——Oh, sorry. I _____ with my cousin in the supermarket.

some restaurants, food and serviceare worse than ______ used to be.

The fans ______ to see the pop singer the whole afternoon, and they won’t leave until he turns up.