On April 16th, astronauts Zhai Zhigang, Wang Yaping and Ye Guangfu came back to Earth from the Tiangong space station ________.
widely
especially
highly
safely
I think picking apples ________ very interesting.
What’s your brother like? ________.
Helen told me that she had some problems _______ his English learning.
I think maths is not ________ science.
---Which pen can I take? ---You can take ______ pen you like.