If he ______ harder, he will catch up with us soon.

Some plants are so difficult to grow that they can only ______ in a perfectly clean environment.

product ____ unsatisfactory within 7 days inany way, you can take it back

下面选项填入横线处，构成比喻最恰当的一项是( )生活中，我们有时会遭遇无意的伤害，但请记住，我们不可为之抛弃了那一颗宽容之心。这就犹如________。

The daytime of the summer is longer than _____ of the winter.