______ a little earlier, I would have caught the train.
A、DidIleaveC
本題考查的是if引導的虛擬條件句，省略了if要把had提前。
NeitherEnglishnorChinese________difficulttolearn.
Thisis________goodreadinghabitsarenotonlyanimportantstudyskillforthestudent,butalsoanimportantlifeskillforanyone.
Touristexpenditureshavedifferenteffectsonadestinationeconomy:salesbyfoodvendorstorestaurantsare_______effect;whiletaxifaresandairlineticketsalesare_______effect.
Scientistsdoubtwhetherit’s________toregulateone’sbiologicalclockbydrinking.
Whichofthefollowingisnotaninternationalvisitor?
