On rainy days, accidents ______ happen sometimes on steep roads．
| A．should | B．shall | C．must | D．can |
_________ appeared to me that he enjoyed the food very much.
| A．What | B．It |
| C．All that | D．That |
_________ all the inventions have in common is _________ they have succeeded.
| A．What; what | B．That; that |
| C．What ； that | D．That ； what |
_________ you don't like him is none of my business.
| A．What | B．That |
| C．Who | D．How |
—How about going to Beijing for our holidays?—That's splendid. _________.
| A．It's really hot | B．It’s none of my business |
| C．I have known it already | D．I'm looking forward to it |
Take short walks to calm down, or, _________，simply take a day off.
| A．if necessary | B．if not |
| C．if ever | D．if so |