题型:填空题 如图所示,一束太阳光经过三棱镜到达白纸做的光屏上,光屏上应该有______种色光;对于流入市场上的假币,人们常借助验钞机发出的______(选填“红外线”或“紫外线”)来辨别真伪.太阳的热主要是以______(选填“红外线”或“紫外线”)的形式传送到地球上的. 查看答案
题型:选择题 I observed a number of _____ children who were taken out of a special class and placed in a regular class. [ ]A. intelligent B. competent C. ordinary D. independent 查看答案
题型:单项选择题 下列物质中,熔点由低到高排列的顺序应该是()。A.NH3<PH3<SiO2<CaOB.PH3<NH3<CaO<SiO2C.NH3<CaO<PH3<SiO2D.NH3<PH3<CaO<SiO2 查看答案