Mangan (VII) oxit có công thức hóa học là
A.$ M{{n}_{2}}{{O}_{7}} $.
B.$ M{{n}_{7}}{{O}_{2}} $.
C.$ Mn{{O}_{2}} $.
D.$ Mn{{O}_{7}} $.

Trong những hình đa diện sau, hình nào không có hình trụ ngoại tiếp?
A.Tứ diện đều.
B.Hình chóp có đáy là hình bình hành.
C.Hình hộp chữ nhật.
D.Hình lập phương.

Choose the answer among A, B, C, D to complete each of the sentences below:
After nine months without any rain, the country was facing one of the worst _______ in the last fifty years.
A.floods
B.draughts
C.droughts
D.eruptions

Choose the answer among A, B, C, D to complete each of the sentences below:
They were________ for smuggling jewelry into the country.
A.warned
B.arrested
C.accused
D.judged

Choose the answer among A, B, C, D to complete each of the sentences below:
Some scientists say that there are enough resources to ______ 8 billion people.
A.provide
B.distribute
C.support
D.raise

Choose the answer among A, B, C, D to complete each of the sentences below:
Dogs make very _______ pets. They'll always stay by your side.
A.loyal
B.private
C.digital
D.mental

Choose the answer among A, B, C, D to complete each of the sentences below:
A trust employee was discovered to have ________ confidential plans to a competing company.
A.spread
B.stolen
C.rumored
D.leaked

Choose the answer among A, B, C, D to complete each of the sentences below:
Learners of English as a foreign language often fail to _______ between unfamiliar sounds in that language.
A.separate
B.differ
C.distinguish
D.solve

Choose the answer among A, B, C, D to complete each of the sentences below:
Like many other baby birds, ducklings are blind _______ birth.
A.from
B.on
C.at
D.of

Choose the answer among A, B, C, D to complete each of the sentences below:
The story about the alien spaceship was _______ to have been invented by jounalists.
A.believed
B.suggested
C.recommended.
D.announced