講解：
switch (in / of sth) | ~ (from A to B)
(尤指突然徹底的)改變,轉變:
She made the switch from full-time to part-time work when her first child was born.
第一個孩子出生后她就從全職工作改為兼職工作。

incentive (for / to sb / sth) (to do sth)
激勵；刺激；鼓勵:
There is no incentive for people to save fuel.
沒有使人們節約燃料的鼓勵辦法。

cut it
(不)如預想的一般好；(不)像所需要的那么好:
He won't cut it as a professional singer.
他的歌藝未達到專業歌手水平。

discourage sth | ~ sb from doing sth
阻攔；阻止；勸阻:
a campaign to discourage smoking among teenagers
勸阻青少年吸煙的運動

necessity (for sth) | ~ (of sth / of doing sth) | ~ (to do sth)
必然；必要；需要:
We recognize the necessity for a written agreement.
我們認為有必要簽訂一份書面協議。