A:had the star arrived
B:the star had arrived
C:has the star arrived
D:the star has arrived
鉴别两瓶失去标签的盐酸和硫酸溶液,可使用下列试剂中的( )
关于青藏地区的叙述正确的是( )①以干旱为主的自然特征 ②河流较少,多为内流河③具有丰富的太阳能资源 ④很多山峰终年积雪,冰川广布