未知题型 'Look at those pretty girls' skirts' is ______, because it is not clear whether the girls or the skirts are 'pretty'.A.ambiguousB.hiddenC.indirectD.indistinct

单项选择题 图示简支梁受到集中力作用（l = a+b），下列结论错误的是（  ）。

未知题型 Why does the author say 'spring cleaning can't wait'?A.Because there will be more activities when it gets warmerB.Because the air is fresher and the breeze is lighter.C.Because the whole family is full of energy at spring timE.D.Because the snow is melting and the ground is thawing.