蛙泳出发和每次转身后，从第一次手臂动作开始，身体应保持俯卧，两肩应与（）平行。
参考答案：水面
-I'm sorry, but there's no smoking in this section on the train.
-Oh, I ________ that, and I won't again.[ ]
A．don't know
B．didn't know
C．won't
D．haven't known
埃里克森认为，信任感是一个人对周围世界的基本态度，它在婴儿期建立，并在以后继续发展。( )
