In our class, when the bell rang and the teacher closed his book, it was a ______ for everyone to stand up.
| A．signal | B．chance | C．mark | D．measure |
---- May I smoke here?
---- If you, choose a seat in the smoking section
| A．should | B．could | C．must | D．may |
There are lots of problems in your hometown, but we're happy to see many of them________.
| A．are solving | B．are solved |
| C．have solved | D．are being solved |
Everyone is different and that is ________ makes our world so much better.
| A．that | B．which | C．what | D．who |
The rich shouldn't ________their wealth. Instead, they should contribute more money to the poor.
| A．show off | B．take off | C．put off | D．give off |
Try to be independent, for your parents can't do __________for you all your life.
| A．something | B．nothing | C．everything | D．anything |