—What's your math teacher like? —_________.
A:He's twenty-seven years old
B:He works in our school 。
C:He's creative and outgoing
D:He likes physics and biology
一定条件下,甲、乙、丙、丁四种物质在密闭容器中反应,测得反应前后各物质的质量分数如图所示,下列说法正确的是( )
地表崎岖,石灰岩广布的高原是( )
我们要观察细菌的结构,应借助于( )