Choose the best option to fill in the blank

----- Nội dung dịch tự động từ ảnh -----
II. Choose the best option to fill in the blank.
1. Wind power is one of the earliest
used by humankind.
sources of energy
A. alternative
B. polluted
C. harmful
D.
exhausted
2. Nobody can predict exactly when supplies of fossil fuels will be
However, we all know they quickly reduce in quantity.
A. installed
B. polluted
C. harmful
D.
exhausted
3. Biogas can be used to
or electrical generation.
natural gas in cooking, heating,
C. pollute
electricity, and for hot
A. use up
B. replace
D. install
4. Solar energy can be used for
water heating.
A. investing
generating
B. polluting
D. installing
C.