Mesectoderm
中外胚层
🗣️ 情景例句
Things look black.
前途暗淡。
Thereis no wool so white but a dyer can make it black.
羊毛再白，也能染黑。
Every day he does the same thing. Why doesn't he use the lift for the last three floors?
每天他都这样度过。为什么上最后3层楼他不用电梯呢？