单项选择题
Read the following noun phrase: those five beautiful shiny Arkansas Black apples sitting on the chair. What is the head noun?
单项选择题 The density of a crystalline polymer will be greater than an amorphous one of the same material and molecular weight because:
判断题 在满足相干条件的光波的相遇区域内，任何一个位置的合成光的强度都不会小于其中一列光的光强。
单项选择题 Who is usually regarded as the first American female poet?
