Mom, I’m old enough to wash ________ own clothes and ________. You can have a rest after work.
________ my surprise, the twins have nothing _______ common.
---Do you know sound travels very fast? ----Yes. But light travels _______ sound.
Paper-making is one of _______ of ancient China.
Could you please give some _______ to the _______ teachers?
Please wait here. I’ll be back in _______ hours.