PM2.5是指大气中直径小于或等于2.5μm的颗粒物,富含大量的有毒、有害物质,易通过肺部进入血液.目前PM2.5已成为空气污染指数的重要指标.下列推测不合理的是( )
A:PM2.5进入人体的肺泡中时还没有进入人体的内环境
B:颗粒物中的一些酸性物质进入人体血液会导致血浆呈酸性
C:PM2.5可能成为过敏原,其诱发的过敏反应属于免疫异常
D:颗粒物进入呼吸道引起咳嗽属于非条件反射,其中枢不在大脑皮层
Many people think that twins are exactly the same. But some of them are not! Al and Mike are twin brothers. They look the same and in some ways they are the same. But in other ways they are different. Al and Mike are both very strong. Al and Mike both like soccer. But Al plays soccer every day and Mike plays soccer only on weekends. Mike likes watching soccer games on TV but Al only likes to play the game, not to watch it. Al and Mike are both outgoing and funny, but Mike is a little more outgoing than Al. Mike is also a little more serious about school. Al and Mike are very popular at school, and they both have a lot of friends.
根据短文内容判断正误.
如图是一个圆柱体,则它的主视图是( )
“能源危机”是当今世界各国共同面临的问题,对此以下措施可行的是( )