两个同心圆环a、b套在一条形磁铁上，如右上图所示，两环半径分别是，且。设穿过a、b两圆环的磁通量分别是(填<、>或=)。
<
根据下列句子所给汉语意思，写出空缺处各单词的正确形式。
1. _______(事实上), on second thought, I don't think I want to go out tonight.
2. He caught a cold yesterday and ______(遭受) from a headache last night.
3. He was too ________(顽固的) to admit that he was wrong.
4. It is surprising that he can speak _______(流利的) English after such a short time in England.
5. Mr. Wang went back to work after he fully ________(恢复) from the operation.
区域勘探的四个步骤依次是（）。
，且
。设穿过a、b两圆环的磁通量分别是
(填<、>或=)。
，且。设穿过a、b两圆环的磁通量分别是(填<、>或=)。