请教名词性从句

九山环一湖

LZM的公理说,名词性从句中IF必错,应用WEATHER.请问名词性从句的含义是什么?

LES

先看看基本语法吧。

http://www.52en.com/whbm/grammar/index.htm

mariezhu

don't understand what he means by noun phrase, however, according to ets, a clause introduced by IF indicates a certain condition, while a clause introduced by WETHER indicates the possibility .