______alittleearlier,Iwouldhavecaughtthetrain.
A、DidIleaveC
本题考查的是 if 引导的虚拟条件句，省略了 if 要把 had 提前。
Bythemiddleofthe21stcentury,thevastmajorityoftheworld’spopulationwillbelivingincities_______inthecountry.
Astothevariouspollutions,whichofthefollowingisNOTtrue?
PoorspeakerofEnglishthoughhewasatthetime,hestillmanagedtomakehimself________.
Hefound_______difficulttostudymaths.
________hehasmanyfriends,heisoftenfeelinglonely.
