倒计时的英语一般用countdown，没有缩写形式。复数是countdowns. 例句 The countdown has begun for the launch of the space shuttle. 航天飞机发射前的倒...
had begun是过去完成时，意为当我到那里时,演出已经开始了.“已经开始”所以用完成时； 例句 My head had begun to ache and my stomach felt funny. 我的头...
start to do sth和start doing sth的区别start to do sth准备开始做某事。是将要做，但是还没有做的状态。而start doing sth某件事已经开始做了，表示已经开...
