如图,在△ABC中,∠B=90°,AB=4,∠BAC的角平分线AD交BC于点D,BD=3,则点D到AC的距离是()
A:2
B:3
C:4
D:5
My friend Amy text messages to me on the mobile phone, but now she e-mails on QQ.
从①氢气、②活性炭、③二氧化碳、④碳酸氢钠中,选择适当的物质填空(填序号)
写出反义词
盛开—____ 休息—____ 笑脸—____