2.Whose is the package I am weighing?答案是Whose is the package being wighed?
这两个句子都对,只不过第一个是定语从句,用的是主动,第二个是非谓语,进行时态的被动的非谓语形式
Whose is the package I am weighing?=Whose is the package which /that I am weighing?
这是定语从句,先行词是package,weigh 理解成及物动词,给谁称量,缺少宾语,因此是关系代词that,which ,并且可以省略
Whose is the package being wighed?=Whose is the package( which is) being wighed?
括弧里给出的是定语从句的解释,然后把主谓去掉,形成了进行时态的非谓语,是被动
3.What is troubling them most is that they have not enough farm tools.
答案是What is troubling them most is their not having enough farm tools.
这两个句子也没错,只是一种手法,同义句转换的手法
原句是表语从句,that 不能省略,that 后面的表语从句不缺任何成分
改过来的句子,is 后面的表语,不是句子,而是一个名词短语,叫复合名词
这个复合名词是这么来的：
enough farm tools 这是名词的词根,然后have 做动名词having (因为is 联系动词,动名词做表语）,形成了having enough farm tools,他的否定是not having enough farm tools,这么长都是名词,那么名词可以用物主代词their修饰,就形成了 their not having enough farm tools.
4.The doctor insisted that I should stay indoors for days 答案是The doctor insisted on my staying indoors fo
两个句子都对,前一句是宾语从句（虚拟,固定的用should +动词原形）
第二个就是非谓语,insisted 后面的宾语部分,就是一名词,压根没动词,也是复合名词
insist on doing sth,这个你必须要懂,有这个固定搭配,然后on 后面的是介词宾语,同理,stay 这个动词就得用动名词,然后动名词用物主代词修饰,my staying indoors
5.My suggesttion is that they should leae as soon as possible .答案是My suggesttion is for them to leave as soon as possible 不是去掉主语 去掉谓语 去掉连词 就好了吗 怎么这道题还加了介词?主语也变成宾语了
如果去掉主语,去掉谓语,去掉连词,就是：
My suggesttion is to leave as soon as possible
这叫不定式做表语（也是非谓语）
但是加了个for sb 这是可有可无的,比如
it is adj (for sb) to do sth
最后一点,关于你对非谓语的理解,有个误区,在这里：“不是去掉主语 去掉谓语 去掉连词 就好了吗 ”
这说明你还没能真正懂,只知道样子是这个样子,可是不知道,去掉之后,还得分析是主动,（现在分词）,被动（过去分词）,主动又是表目的或者将来（ 不定式）,关键在于分析这几点
另外,这个连词有事可以不必去掉,直接跟非谓语,也是常见的