

Mn giúp mình câu này với ạ, lâu không đụng tới ngữ pháp nên mình quên sạch rồi, huhu.
It;s vital that the United States ______ on improving its public education system. What we do now will affect our country for generations to come.
a) focuses
b) focus
c) focusing
d) to focus
It;s vital that the United States ______ on improving its public education system. What we do now will affect our country for generations to come.
a) focuses
b) focus
c) focusing
d) to focus