A. variety
Đáp án A
- A (wide) variety of + N số nhiều: nhiều
The emphasis is on oral communication practice in a wide variety of situations at the advanced knowledge (Trọng tâm là thực hành giao tiếp trong nhiều tình huống khác nhau ở mức độ kiến thức nâng cao)
Scientists are unsure of the reason for this (27) ¬________ on the global scale either.
In time of (27) __________ transportation can rush aid to persons in areas stricken by floods, families and earthquakes.