老师们常认为青少年工作者纪律性差且能力低下。Teachers often view youth workers as undisciplined and ineffectual.他体质太差，爬不到山顶。He was too out of condition to clamber over the top.居民们普遍都很贫穷，受教育程度低，居住条件较差。Residents in general are poor and undereduc...
At this point esch chromosome consist of a pair of chromatids and the two associated chromosomes are termed a tetrad.此时每条染色体由一对染色单体构成,这两条联合的染色体称为四分体.The Y chromosome is starting to yield other intriguing tales as well.Y染...