4个回答
1、My suggestion is more attention should be attached to the issue of youth drug abuse.
*is是系动词，后跟表语从句，that引导表语从句时不能省略，这里少了that.
*主语是suggestion,advice等表示建议，命令的词从句应当用虚拟语气，并且should要省略。
2、People think developing space research well spend a huge number of money.
*spend表示花费时间或金钱时主语应当是支付者，是人，cost的主语才是物，这里是说发展太空研究会花费大量金钱。主语是物，应该改成cost.（will打错咯！！）
*a large/huge/great number of只能修饰可数名词，money不可数，所以错了。改成huge amounts of吧。
3、Now people go abroad becomes very easy.
*这句句子有两个动词，肯定不对，become是真正的动词，句子意思是现在人们出国变的很容易。要不然就把become前面的部分变成主语从句,用that引导，That people go abroad now becomes very easy.要不然就把它变成动名词短语，就可以做主语了。Now people's going abroad becomes very easy.
4、When one is over 70 years old, he is very dangerous if left alone at home.
*当人超过70岁的时候，一个人独自在家是很危险的。错在he is very dangerous,他不是怪兽啊，怎么能说他很危险呢？所以应该改成it is very dangerous if he is left alone at home.it是形式主语，真正的主语是if he ...并且这里if从句当中的he不要省略，否则从句的主语都不知道到哪里去找拉~。
回答完毕，不懂再问^^
My suggestion is that more attention should be attached to the issue of youth drug abuseness
2、People think developing space research well cost a huge number of money.
Nowadays people go abroad becomes very easy
When one is over 70 years old, it is very dangerous if he is left alone at home
1、My suggestion is that more attention should be attached to the issue of youth drug abuse.
2、People think that developing space research will spend a huge number of money.
3、Now going abroad becomes very easy for people.
4、When one is over 70 years old, it's very dangerous to leave him alone at home.
1、My suggestion is that more attention should be attached to the issue of youth drug abuse.
此句用了虚拟语气和主语从句，主语从句THAT不可省！
2、People think developing space research will spend a huge deal of money.
money不可数不可用a number of 修饰
3、Now going abroad becomes very easy.
主语不清，应为going abroad而不是people
4、When one is over 70 years old, it is very dangerous if left alone at home.