— Can I tell Peter about the news?
— No, I don't want anyone else to know it. You_____ keep it to yourself.

I'm feeling much better now, so you ______ call the doctor.

— _______ I have a ticket, please?
 — Sorry, sir. All the tickets were sold out ten minutes ago.

— Wow! You look different! You______ wear glasses.
 — Yes, I did. But now I am wearing contact lenses(隐形眼镜).

They ______ play football last Friday because Simon forgot to bring his football here.

Trees ______fight air pollution. They are natural air conditioners.

甲、乙两人同时同地沿400米环形跑道反向而行，经1分20秒相遇，如果两人同时同地同向而行，甲跑3圈就追上乙。甲每秒跑（ ）米

甲、乙两车同时从A、B两地相向而行，甲车每小时行56千米，乙车每小时行48千米，两车在距中点32千米处相遇，A、B两地相距（ ）千米？

甲、乙两列车同时从东、西两地相对开出，第一次在东面75千米处相遇，相遇后两列车继续行驶，到达目的地后又立刻返回，第二次相遇在离西面45千米处。东、西两地相距（）千米？

快、慢两车同时从两城相向出发，4小时后在离中点20千米处相遇。已知快车每小时行70千米，慢车每小时行（）千米？