题目

读下面短文，从短文后各题所给的四个选项(A、B、C和D)中，选出可以填入空白处的最佳选项。 To be a good teacher, you need some of the gifts of a good actor: you must be able to 1the attention and interest of your students, you must be a 2 speaker, with a good, strong pleasing voice which is fully under your control; and you must be able to3what you are teaching, in order to make its meaning clear. Watch a good teacher, and you will see that he does not sit still 4 his class: he stands the whole time he is teaching; he walks about, using his 5 , hands and finger已知同一平面内的直线L1，L2，L3，如果L1⊥L2，L2⊥L3，那么L1与L3的位置关系是 [     ]A．平行B．相交C．垂直D．以上全不对