Homochroman
高二氫苯并吡喃
??? 情景例句
Pretty good, but I got caught in a traffic jam in Beijing.
很好，不過在北京碰上了交通阻塞。
Do one's level best.
盡力而為。
Please do. We 're desperate for the material.
麻煩你了，我們非常需要這些材料。