【简答题】看图填空,一空一词。 1. What can you see in the picture? We can see that a school ______ ______ a skating Marathon. 2. How many people are there in the picture? And who are they? There are seven. Five are stude...
【简答题】如图,在长方体 ABCD A 1 B 1 C 1 D 1 中,已知 AB =4, AD =3, AA 1 =2, E , F 分别是棱 AB , BC 上的点,且 EB = FB =1. (1)求异面直线 EC 1 与 FD 1 所成角的余弦值; (2)试在面 A 1 B 1 C 1 D 1 上确定一点 G ,使 DG ⊥平面 D 1 EF .