Peter is my best friend. He often helps___ science.
-–I called you yesterday evening, but there was no answer.-- Oh, I am sorry I dinner at my friend's home.
-- How long can I this book?-- For three days.
This is the place Lu Xun has lived in.
-–I need a pen to write down the address.---A pen? OK, I'll get for you
—I have a meeting to attend. I have to go first.-- It’s raining hard. until it stops or you will get wet.