41 I’m under explicit _______ to keep my mouth shut about his opinions.
(A)illusion
(B)implication
(C)instruction
(D)innovation

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41 I’m under explicit _instruction______ to keep my mouth shut about his opinions. 

explicit==>向外疊的。=>詳細的。

explicit (形) instruction (教導，指示)

to keep my mouth shut ==>不定詞。表示要達成的目的。

i  am under==>現在正經歷,處於…情況

因此是   i am under explicit instruction(我正在經歷詳細的教導(指示) 為了要達成使我閉嘴的目的。

也就是這個SHUT是被關上。 後面的 about his opinions，是instruction的有關。

因此這句是說

我正在經歷詳細和有關他的意見的教導(指示)，為了要達成使我閉嘴的目的。

under是說 處於什麼狀態。

(A)illusion 
(B)implication 
(C)instruction 
(D)innovation

I am under explicit instruction.

我被授予明確指令；我被明確授令。

explicit 1

詳盡的；清楚的；明確的

explicit （a）清楚的，明確的

I wasn't aware that I would be paying - you certainly didn't make it explicit (= state it clearly).

我不知道要付錢——很明顯是因為你沒說清楚。

illusion（n）幻覺，幻想

I'm under no illusions (= I understand the truth) about the man I married.

我對我所嫁的男人不抱幻想。

implication （n）牽連；暗示

[ + that ] From what she said, the implication was that they were splitting up.

她的話暗示他們將要分手