【单选题】All the parents worry about the() of TV on their children.
【单选题】He is a ________and well-behaved child, but his parents worry about him for he talks too little.
【单选题】—Is it that Jack often plays computer games makes his parents worry about him ? —Yes , I think so .
【单选题】1953年Watson和Crick发现DNA双螺旋结构,标志着生命科学进入了( 阶段)
【单选题】1953年,Watson和Crick发现了
【单选题】Watson和Crick发现了DNA双螺旋的结构,开启了分子生物学时代,使遗传的研究深入到分子层次,“生命之谜”被打开,这项成果发表时间是( )