I put the medicine on the top of the desk to make sure it would not be _____ to my son.

It is human activity has caused this global warming.

________ times a week do you go to the library — Twice a week.

We are so sorry for thatWe’lltry to determine exactly _________ went wrong that evening

People try to avoid public transportation delays by using their own cars, and this ________creates further problems.(2007· 湖北)