单选题 The director had her assistant ______the memo.

A、 (A) signing
B、 (B) signed
C、 (C) will sign
D、 (D) sign

【正确答案】 D

【答案解析】The assistant is the one who signed the memo, so the simple form of the verb is used. Choice (A) is the present participle. Choice (B) is the past participle. Choice (C) is the future tense.