The children ＿＿＿＿＿＿ very quiet, I wonder what they ＿＿＿＿up to. A.were, are being
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The children ＿＿＿＿＿＿ very quiet； I wonder what they ＿＿＿＿up to.
A.were； are being B.are being； are C.are； do D.are being； do
试题答案
B
解析:
be用于进行时可表示一个暂时的特点或表现。What they are up to相当于What they are doing。