系动词be的用法

系动词be的用法

(一)be的时态变化

系动词be会有一般现在时、一般过去时、一般将来时、现在完成时、过去完成时等的时态变化。如：

He isa student.

They werein the park yesterday.

It will be cloudy tomorrow.

He has been ill for six days.

It had been three hours before she left the hat shop.

(二)be与情态动词的连用

其用法为：情态动词+系动词be原形。如：

It must be Lucy's book. Her name is on the cover.

It can be very difficult for us to memorize too many words within such a short time.

She should be here on time tomorrow.

系动词可接哪些词语作表语：

连系动词后的表语通常是名词和形容词，有时也可以是代词、数词、副词、介词短语、不定式、动名词、从句等。如：

1. 用名词作表语。如：

Translation is an art. 翻译是一种艺术。

Beijing is a beautiful city. 北京是一座美丽的城市。

2. 用形容词表作语。如：

Traveling is interesting but tiring. 旅行是有趣的，但是使人疲劳。

Every hour and every minute is important. 每一小时，每一分钟，都很宝贵。