His pronunciation is better, for he kept ______ a short passage after the tape every morning.

Air quality in our city is becoming worse and worse. – Yes. These days’ PM2.5 readings are frightening. We must do something to _______ air pollution.

Can I use your bike this afternoon?_______ is under repair.－No problem. Here’s the key.

People _______ pale skin and blonde hair look good _______ yellow and pink.

I think skiing is ____ great fun.