单项选择题
There are ________ periods in an animal’s life when it is capable of learning a great deal in a very short time.A) urgentB) violentC) seriousD) critical
单项选择题 The word “fallacy” (Para. 2. L. 6) means ________.A) doubtB) factC) strong argumentD) wrong belief
单项选择题 Part of the cost of many articles is taken as tax by the government ________ the community.A) in place ofB) on account ofC) in terms ofD) on behalf of
单项选择题 在C语言程序中，定义无符号型变量的关键字是（）。
