介绍:
Key Sentence重点句型
There be句型，表示“某地有某物”
句式1-There is +单数可数名词/不可数名词
例如：
There is a sandwich in the lunch box.
There is some rice in the lunch box.
(lunch box 为午餐盒/便当盒)
*a sandwich为单数可数名词，rice为不可数名词
句式2-There are +复数可数名词
例如：
There are some carrots in the lunch box.
There are some onions in the lunch box.
*carrots和onions为复数可数名词
