Sometimes it often rains _____ in my hometown in summer.

___ is left over may be put into the refrigerator, ____ it will keep for two or three weeks.

下列各句中，没有语病的一句是（ ）

It is usually not quite cold in this area in March，but sometimes temperature ______ low.

The scientists are beating their brains, trying to ______ a solution to the problem.