8. Astragalus (Huang Qi) contains beneficial plant compounds that may ________ your immune system.
(A) reinforce
(B) enforce
(C) mitigate
(D) petrify

8. Astragalus (Huang Qi) contains beneficial plant compounds that may _reinforce__ your immune system.黃芪含有有益的植物化合物，可以增強您的免疫系統。

(A) reinforce ;to make something stronger
加固；使更結實 re再 + enforce (vt.)實施;強迫 
The pockets on my jeans are reinforced with double stitching.
我牛仔褲的口袋縫了兩道線，很結實。

(B) enforce (vt.)實施;使服從（法律）;（強制）實行，執行，把…強加於。 ; to make people obey a law, or to make a particular situation happen or be accepted
= en + force(vt.)強迫
It isn't always easy for the police to enforce speed limits.
對員警來說，嚴格執行限速規定並不總是件易事。
The new teacher had failed to enforce any sort of discipline.
這位新教師一點都管不住學生，搞得紀律渙散。

(C) mitigate;to make something less harmful, unpleasant, or bad
(vt.)鎮靜;使緩和；減輕（危害等) = mild (adj.)溫和的 + ag(使動作) + ate 動詞) 
It is unclear how to mitigate the effects of tourism on the island.
人們還不清楚如何減低旅遊業對這個島嶼的影響。

(D) petrify;to frighten someone a lot, especially so that they are unable to move or speak把…嚇呆，使驚呆 = petrous (adj.)岩石的 + fy(使成為)
I think you petrified poor Frazer - he never said a word the whole time you were here.
我想你把可憐的弗雷澤嚇呆了，你在這裡的時候他一句話也沒說。
Ans.:(A) reinforce