You are not allowed to camp here without ________（允许，许可）.
Nowadays people use ______ (信封) less and less because they turn to other forms of communication rather than write letters.
To be frank, we all have our strengths as well as ______ (弱点).
It is the ________（风俗）for westerners to celebrate Christmas.
It was getting darker and darker, we waited anxiously for the ________（到达）of the next bus.
I know you don’t like her but try not to make it so _________（明显的）.
We asked the stranger the question out of ______(好奇).
My sister, an inexperienced rider, was found sitting on the bicycle trying to ________（平衡） it.
He is not a wealthy person; on the ________（相反），he has been in heavy debt..
Thank you for ______（提醒） me about my appointment..