根据句意从括号中选择正确的单词并填写在空白处。

Not so many years ago, you ________(hard, hardly)ever saw air-conditioners．

Let me ________(show, to show, showing)you around the city．

I don't like traveling by boat, it always makes me ________(to feel, feeling, feel)sick．

She has a nice voice．I often hear her ________(singing, to sing, sing)in the morning．

I'm sorry to have kept you ________(to wait, waiting, wait)for such a long time．

Mike managed ________(to give, giving, give)up ________(to smoke, smoking, smoke)．

I'd rather ________(to have, having, have)a cup of coffee．

People must stop ________(to cut, cutting, cut)down trees．

The man admitted ________(rob, to rob, robbing)the bank．

He is not old enough ________(to go, go, going)to school．