As we all know, smoking too much can _____ cancer and many other illnesses.

After climbing the hills in the natural park for hours, my legs _   under me and I failed to keep pace with others．

Although some unexpected difficulties have ________ in the process, we are confident that we can handle them.

During the press conference, the president _____ the message that the government is well aware of the problems that the country is facing and is trying to deal with them.

— Jimmy had a lot of parties recently. — Yes, that might       why he didn’t do well in the test.