A-A+
Researchers discovered that plants infected wi
问题详情
Researchers discovered that plants infected with a virus give off a gas that ______ disease resistance in neighboring plants.
A．contracts
B．activates
C．maintains
D．prescribes
参考答案
正确答案：B
解析：动词辨析。contract意为“感染”；activate意为“刺激、使活动”；maintain意为“维持”； prescribe意为“规定、开处方”。根据句意应选activates。
