1.改正：Hesucceededinthecompetition,whichmadeeachofushappy.

　　或：Hesucceededinthecompetition,makingeachofushappy.

　　不能用两个动词同时做一个简单句的谓语.

　　要么把句子变成复合句,要么把某个动词变成非谓语形式.

　　2.改正：Theproblemisthatmoreandmoreyoungpeoplearegettingintothehabitofsmoking.

　　表语从句的that不能省略.

　　3.改正：Whetherheisanengineerisunkown.

　　主语从句的“是否”只能用whether,不能用if.

　　4.改正：Whatshewantstoknowiswhethersheshouldattendtheconference.

　　表语从句的“是否”用whether,不能用if.

　　5.改正：Atthemeetingheraisedaquestionwhethertheprojectwouldbecancelled.

　　同位语从句的“是否”用whether,不能用if.

　　6.改正：Itdependsonwhetherit'sgoingtorain.

　　介词后的宾语从句的“是否”用whether,不能用if.

　　7.改正：WeexpressedthehopethattheBrownswouldcometoChinaagain.

　　同位语从句的引导词t不用which用that.

　　8.改正：Thereasonwhyhefailedintheexamwasthathewastoocareless.

　　用表语从句来解释原因时,引导词用that,不用because.

　　9.改正：Whoevercomestovisittheexhibitioniswelcome.

　　nomatter不能引导主语从句,但是whoever可以.

　　10.改正：WhatheneedsisenoughtimeandwhatIneedareenoughbooks.

　　what引导的主语从句,动词的数应该根据事实来判断.