B. playing ("Look!" indicates a present continuous action.)
D. go (The correct collocation is "go swimming.")
D. best (This is a superlative form: "the best job.")
B. are ("There are" is used with plural nouns.)
B. cooler (This is a comparative form: "cooler than.")
D. desert (Deserts are dry areas with little rain and few plants.)
C. jogs (This is the present simple form for the third person singular.)
A. gathering (Tet is a time for family gatherings.)
C. are going (This indicates a future plan.)
C. shouldn't ("Shouldn't" expresses advice against doing something.)
Mrs. Nga usually watches TV after dinner. (Present simple, third person singular)
We must not play soccer in the street. (Modal verb "must" is followed by the base form of the verb)
How about helping old people? ("How about" is followed by the gerund form.)
There are not two bedrooms in Nga's house. (Present simple, plural)
I think they will walk to school tomorrow. (Future simple, expressing a prediction)