Millions of red envelopes(红包)____out on the eve of the Spring Festival.
There are two cars in front of the building. One is red and ________ is black.
If more trees ________ , our city will be more and more beautiful.
This brush pen is made _______ bamboo.
Although he lives _______ , he never feels ________ .
--- _______ are they talking about? --- Our English teacher. A. Whom B. What C. whose D. When