$\text{1.}$ What about playing badminton?
$\text{→}$ What about + V-ing?
$\text{2.}$ Hong is not as young as Hoa.
$\text{→}$ S1 + be/ V + (more) + adj/ adv(-er) + than + S2 = S2 + be/ V(-) + as + adj/ adv + as + S1
$\text{3.}$ Where do you live?
$\text{→}$ What is one's adress? = Where do/ does + S + live?
$\text{4.}$ He is strong enough to carry that suitcase.
$\text{→}$ adj + enough (for sb) to-V
$\text{5.}$ Hung isn't as tall as Long.
$\text{6.}$ Why don't go out tonight?
$\text{→}$ Why not + V?
$\text{7.}$ He is not heavy enough to lift all those suitcases.
$\text{→}$ too + adj + (for sb) to-V = not + adj + enough + (for sb) to-V
$\text{8.}$ Minh is a careful driver.
$\text{→}$ S + V + adv = S + be + (a/ an) + adj + N
$\text{9.}$ He is a good student.