【C19】A．asB．whichC．thatD．when

【C6】A．whereB．whichC．thatD．as

A．whatB．whichC．thatD．since

【29】A．whatB．whichC．thatD．if

The only candidate______ can hope to defeat him finally quits.A．whoB．whichC．thatD．when

【C10】A．AsB．WhichC．ThatD．Who

______ we all know air is gas.A.AsB.WhichC.ThatD