A-A+
A bone marrow test (what) (involves) extracti
问题详情
A bone marrow test, (what) (involves) extracting fluid from the marrow, (maybe) necessary (for diagnosing) leukemia.
A．what
B．involves
C．maybe
D．for diagnosing
参考答案
正确答案：A
解析：what不引导定语从句。引导非限制性定语从句应用which。改“what”为“which”。
