I need more careful.和I need to be more careful.I need play football和I need to play football

实意动词,情态动词------共2种类
she needs to buy a book.
she doesn't need to buy a book.
does she need to buy a book?
what does she need to do?
实意动词用法,用助动词提问
she need buy a book.
she needn't buy a book
need she buy a book?
what need she do?
情态动词用法,直接对情态动词本身提问
但是情态动词need多用于否定和疑问
所以句一,是为了举例,一般不用,剩下的3个是常用的,否定和疑问
i need be more careful