形状为等边三角形、顶角朝上,颜色为黄底、黑边、黑图案的是警告标志。
参考答案：对
—Is Mike at home?
—No. He _______ with his brother.
A．swims
B．was swimming
C．is swimming
D．swam
贲门失弛缓症(achalasia)
