域名是分层次的，每层之间用“.”分隔，最左侧的是最高层域名。 ( )
参考答案：错
_____ his parents are at home, he cooks by himself. [ ]
A. If
B. Even though
C. As if
D. Whether
青藏地区主要自然特征为[ ]
A．高寒
B．干旱
C．湿润多雨
D．植被繁茂
