Astronomers estimate ________ called the Pleiades in the constellation Taurus is 415 light years away from Earth．A.that a loose cluster of starsB.a loose cluster of stars isC.that is a loose cluster of starsD.there is a loose cluster of stars
网友回答
A解析estimate是及物动词，后面的空格应该是宾语，或者宾语从句。A项从句的谓语是后面的is。B、C、D项其谓语和后面的谓语矛盾了，一个句子只能有一个谓语。