—What's the matter with John? He has been sitting there for hours．
—A postcard from his father an attack of home - sickness in him．
| A．took up | B．set off | C．brought in | D．built up |
When you are reading，make a note of ________ you think is of great importance.
| A．which | B．that |
| C．what | D．when |
I’d like to work with ________ is honest and easy to get on with.
| A．who | B．whoever |
| C．whomever | D．no matter who |
Water，which seems so simple and common，is ________ makes life possible.
| A．what | B．that |
| C．which | D．how |
I just wonder ________ that makes him so excited.
| A．why it does | B．what he does |
| C．how it is | D．what it is |
________ caused the accident is still a complete mystery.
| A．What | B．That | C．How | D．Where |