单项选择题
A.家庭结构是社会结构的基本单位,它随着社会的发展而变化。 B.家庭结构是社会结构的基本单位,同社会一起向前发展。 C.家庭是社会的基本单位,其结构随着社会的发展而变化。 D.家庭是社会的基本单元,同社会一起向前发展。
A.people have to run on feet when using the machines B.they were faster than running men C.the riders could run on the bicycles D.the bicycles could run fast automatically
A.Different Kinds of Bicycles. B.Modern Bicycles are Safer than the Old One. C.History of Bicycles. D.Invention of Rubber Tyres.