木炭、红磷、硫粉在氧气中燃烧产生的共同现象是（ ）
A．都产生了白烟
B．都放出了热量
C．都有火焰出现
D．都有气体生成
答案：B
—Come in, please. Make yourself at home.
—______.
—I’m glad you like it. [ ]
A. Thanks. You have a nice place here.
B. Oh, this picture is so beautiful.
C. Thanks. What nice food you’ve prepared！
D. OK. Let me look around your new house.
下列物质是由分子构成的是 [ ]
A．二氧化碳
B．金刚石
C．铁
D．氯化钠
