He is very humorous, while his brother is rather serious. That is ___their difference lies.
How can I ________ money from my bank account to his?
For our middle school students, some courses are compulsory, while others are ________.
Someone is ringing the doorbell. Go and see ___________.
One ought __________ for what one hasn’t done.
Luckily good things _________ here to save local wildlife.