Question

 (2011年陜西寶雞檢測)Mary，I should tell you it is the third time that you________.

A．forgot to do                         B．forgot doing

C．have forgotten to do             D．had forgotten doing

Answer 1

解析：選C�？疾闀r態(tài)和非謂語動詞�！癐t is(was)the＋序數詞＋time＋that從句”，表示“是某人第幾次做某事”。在此句型中，若前面為it is，則that從句用現在完成時；若前面為it was，則that從句用過去完成時。而forget to do sth.表示忘了應去做某事，forget doing sth.表示忘了已做過某事。根據語意可知此題應選C。