铝及铝合金焊前必须仔细清理焊件表面的原因是为了防止（）。
Hetalkedalotaboutthingsandpersons________theyrememberedintheschool.
Hermothercan’tspeakEnglish________French,butisgoodatJapanese.
________youhadbeenhere,wewouldn’thavehadsomuchtroublethen.
Thereply,whenitfinallycame,was________thenegative.
EugeneO’Neill’sfirstfull—lengthplay,(),wonhimthefirstPulitzerthemeisthechoicebetweenlifeanddeath,theinteractionofsubjectiveandobjectivefactors.