太阳活动对地球的影响是[ ]
A．诱发地震和潮汐现象
B．诱发台风和海啸
C．干扰电离层和有线通讯
D．产生“磁暴”和“极光”
答案：D
____________, they have been struggling against the snowstorm for ten hours.
A．Up to now
B．By the time
C．From then on
D．In the future
梅尼埃病眩晕多呈突发_________，患者感_________或_________沿一定方向与平面旋转。
