语法-2020-10-10

He believes that [ ( (this very difficulty) (may have had) （the compensating advantage） 
(of forcing him  to think (long and intently) about every sentence),and thus enabling him 
to detect errors (in reasoning and in his own observations) ].
主谓宾语从句 （宾语从句还是个主谓宾且有个and连接）

This alone demonstrates [that (the television business) ( is not) ( an easy world (to survive in)).]

A fact (underlined by statistics) shows [that out of eighty European television networks no less

than 50% (took a loss) ( in 1989) .]

I wonder [ if (I) (can pass) (the National postgraduate Entrance Examination) (smoothly). ]

if只能当宾语从句的引导词，whether 可以当 主语，宾语，表语，同位语从句的引导词

She said (that) she would marry an old rich man.

宾语从句的that可以省略 但是 主语从句，表语从句 和 同位语从句的 that 不可以省略。