I visit twice a year.

我每年去两次。

The children went to camp twice a year.

孩子们每年去两次露营。

Twice a year he goes to camp where he meets other children his age.

他每年两次去营地，在那里遇到同龄的孩子。

He donates blood twice a year to help those in need.

他每年捐赠两次血液来帮助有需要的人。

The snake is a seasonal shedder and sheds its skin twice a year.

这条蛇是一个季节性的脱落者，每年脱皮两次。

You should have your teeth checked by a dentist at least twice a year.

你应该每年至少请牙医检查两次牙齿。

Once or twice a year

一年一两次

I see them twice a year.

我一年会和他们见面两次。

Exam panic, twice a year.

每年两次考试前恐慌。

We can take a vacation twice a year.

我们每年休假两次。