in与at在表时间的区别和用法

in时间范围大（一天以上）如inTanuary,inwinter,in1999；泛指在上午，下午，晚上，如inthe morning.

at时间最短，一般表示点时间，如atsixo’clock,atthreethirty.习惯用法atnight,atnoon.

The new test should aid in the early detection of the disease.

新的化验应该有助于早早检查出这种疾病。

This will not be possible in the changed economic climate.

这在经济气候已经改变的条件下是不可能的。

The weather is very changeable at this time of year.

年年在这个时候天气都变化无常。

Almost all homes have at least one TV set.

差不多每家都至少有一台电视机。