高一英语单词拼写（实在想不起来了,

高一英语单词拼写（实在想不起来了,
On this o_____,however,it had slowed down considerably.
A good command(运用能力;掌握) of English e_________you to communicate with foreign businessmen freely.
They have been told that rescue oprations are p______smoothly.
He said that someone might be spying on the station and the pilot was ordered to keep t________of the strange object.