To be 的用法可以寫一本書.
To be 是不規(guī)則動詞,你必須熟練掌握它的各種形式：
am , is , are , was , were , is being , has been , should be , could be , would be , might be , shall be , will be , can be , must be , need to be ...
輕易得到的東西你不會珍惜,所以我就不多說了.
它的用途主要有：
1. 系動詞,相當(dāng)于“是”
例如：The flower is red .
2. 表存在,
例如：China is in Asia .
3. 表判斷（是/否）,
例如：Are you there ? Yes , I am .
在學(xué)習(xí)過程中,你還會發(fā)現(xiàn)它的許多用法.對 to be 的掌握程度（不僅僅是背下來）是你英語水平的標(biāo)志之一.