beharmfulfor还是to

smileat还是to动词smile可以接介词on,at和to.smileto给...一个微笑,抛一个微笑smileat对...微笑smileon上级/上天对下级/平民的微笑例：Theyoungmansmiledtohisparentsas

Necessary+for还是to?Necessaryforsb.todosth.it'snecessaryforsbtodosthNecessary接for和to都可以的都属于通常用法例Oxygenisnecessaryforlife.氧

limitsbtodo还是todoingtodoing,to在这个短语中是个介词.后面跟动词的ING形式.todo.limitsbtodotodoing绝对正确

chanllengesbtodo还是todoing?challengesb.todosth.cahllengesb.tosth.e.g.Shechallengedmetoplayanothertennisgame.她向我挑战要我跟她再打一场

lookforwardtodoing还是todo?lookforwardtodoing这里的to是介词,不是不定式!切记!

tobesucceed还是tobesuccess?两个都不对.tobesuccessful（形容词）或者tosucceed(动词).tobesucceed均可阿!看你怎么用吧!tobesucceeded或tobesuccesssuccess

contributetodo还是contributetodoing?一般是contributetosth后面一般跟名词,但是跟动名词doing也行,应为to是介词,后面肯定不能用do(动词原形)我晕,楼上的在误人子弟吖!一定要记住to是介词

devotetodo还是devotetodoing?doingdevotetodoingdevotetodoingto是介词，要加动词ing

toussurprise还是tooursurprise第二个后者。。。。。后者，因为toone'ssurprise2ourtooursurprisetooursurprise第二个正确our英咖喱系，搞不懂

adapttodo还是adapttodoingadaptto中的to是介词而不是构成动词不定式,所以后面应该跟doing.不过这个词组后面一般直接跟动词,通常直接接名词或介词的.adapttodosth.---适合做...如:Doyouth

LOOKforwardTO还是LOOKFORWARDSTOLOOKforwardTO

benefit加todo还是todong就是只有sthbenefitsb.和sb.bebenefitfromsth.或者是benefitsth.吧……

tobeblame还是只有toblametoblame

是"tothepresent"还是"topresent"?Tothepresent到了现在uptothepresent直到现在topresent没见过...有presentto,意思是“出现在”；“送给”；“把……呈现给”

Tobehealth还是tobehealthytobehealthy正确be动词后面接形容词healthy作表语,表示“为了（保持）健康”.behealthyhealthy是形容词嘛，加在be动词后tobehealthytobehealth

bedueto还是duetobedueto:由于,因为例句与用法:1.Thefailureoftheschemewasduetobadmanagement.计划的失败是由于管理不善.2.Heacknowledgedthattheaccide

whattodress还是whattowear要先弄明白dress和wear的区别wear和dress表状态,wear接衣服等,可用进行时,dress接人,bedressedin,puton表动作It'scoldoutside.Putony

dobadto还是dobadlytodobadto对……有害,反义词是dogoodto对……有益bad,这里bad是名词badly

whotoask还是whomtoask肯定是whomtoaskwho表主语不是宾语而toask似乎是不定式表被动的用法所以因改用宾语所以选用whomtoask（去问谁）

committodo还是committodoingcommittodoing,to为介词.Willyoucommittome?你会承诺我吗?Committoaccomplishingalltasksinasuperiorway.努力以更好的