$\text{41.}$ He is interested in English.
$\text{→}$ be interested in + N/ V-ing
$\text{42.}$ They participate in outdoor activities.
$\text{→}$ take part in = join in = participate in: tham gia
$\text{43.}$ He looks after sick children.
$\text{→}$ take care of = look after: chăm sóc
$\text{44.}$ They join in playing marbles.
$\text{45.}$ How about going to the zoo?
$\text{→}$ Let's + V = Why not + V? = What/ How about + V-ing? = Shall + I/ we + V? = would like
$\text{46.}$ What about going swimming?
$\text{47.}$ Why don't play chess tonight?
$\text{48.}$ Let's listen to music.
$\text{49.}$ How about going to the cinema with me tonight?
$\text{50.}$ Let's go by car.