By the time my mother came back from work, my sister and I supper and were waiti
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By the time my mother came back from work, my sister and I supper and were waiting for her at the table.
A．have cooked B．were cooking C．had cooked D．would cook
试题答案
C
考查动词时态。根据句意“我母亲上班回来时发生在过去，而我姐姐和我做好饭发生在母亲回来之前，故用过去完成时。”