【单选题】轴外物点发出的( )光束,水平方向和竖直方向的光线的聚焦点在不同平面上,称为像散。
【单选题】I find this Math problem very ______. I believe students can work it out ______.
【简答题】He is easily _______ so I do not like to talk with him. A.defended B.afforded C.created D.offended
【单选题】将下列单词或词组正确排序: as a result , I , passed the exam , worked hard , I , easily , and
A.
I worked hard ,and as a result ,I passed the exam easily.
B.
I passed the exam easily,and as a result ,I worked hard .
【判断题】雾霾天佩戴口罩出门,一定程度降低对人体的危害。
【单选题】I find the computer s ______ to play. [ ]
【单选题】最近,雾霾天气成为热门事件之一.随着空气质量的恶化,雾霾现象越来越严重,对人体的危害也在加重.下列有关雾霾与人体健康的说法中,不正确的是( )
A.
用鼻呼吸,鼻毛能有效阻止雾霾中的颗粒物进入体内
D.
雾霾天气的形成与过度不当燃烧、汽车尾气排放等有关
【单选题】由细颗粒物造成的灰霾天气对人体健康的危害甚至比沙尘暴更大。由细颗粒物造成的灰霾天气对人体健康的危害甚至要比沙尘暴更大。粒径10微米以上的颗粒物,会被挡在人的鼻子外面;粒径在2.5微米至10微米之间的颗粒物,能够进入上呼吸道,但部分可通过痰液等排出体外,另外也会被鼻腔内部的绒毛阻挡,对人体健康危害相对较小;而粒径在2.5微米以下的细颗粒物吸人人体后会进入支气管,干扰肺部的气体交换,引发包括哮喘、支气...