答案是B

21.—CanyoucometoapartyonSaturday,Peter

—Oh,______I'malreadygoingout,I'mafraid.

A.whatapity!B.don'task!C.howcome?D.sowhat?

22.IfyoucometovisitChina,youwill______acultureofamazingdepthandvariety.

A.developB.createC.substituteD.experience

23.______scientistshawlearnedalotabouttheuniverse,thereismuchwestilldon'tknow.

A.OnceB.SinceC.ThoughD.Unless

24.JustasIgottotheschoolgate,IrealisedI______mybookinthecafe.

A.haveleftB.hadleftCwouldleaveD.wasleaving

25.Ashipinharborissafe,butthat’snot______shipsarebuiltfor.

A.whatB.whomC.whyD.when

36.I’mso______toallthosevolunteersbecausetheyhelpedmyterribledayendhappily.

A.specialB.superiorC.gratefulD.attractive

27.______thedifferencebetweenthetworesearchfindingswillbeoneoftheworstmistakesyoumake.

A.IgnoreB.IgnoringC.IgnoredD.Havingignored

28.Someexpertsthinkreadingisthefundamentalskillupon______schooleducationdepends.

A.itB.thatC.whoseD.which