不完全的燃烧和不适当的通风条件能导致乙炔的产生.Incomplete combustion and improper draft conditions can cause ethylene formation.这种反应构成了制备芳基环丙基乙炔的有效方法.This sequence constitutes an efficient method for preparing arylcyclopropylacetylenes.丙二烯是甲基乙...
A beneficent microclimate brings out the camellias betimes ( John Russell )有利的小气候使山茶花提前开放 ( 约翰罗素 )He rose betimes in the morning.他一大早就起床.She writes local items betimes.她有时写点地方性文章.He started betimes in the morning.他一大早就上路...