In HSK 3 grammar, under 词类 → 动词 → 能愿动词, the forms include: 需要、该、应该、愿意、得.
需要
xūyào
to need
该
gāi
should
应该
yīnggāi
愿意
yuànyì
to be willing
得
de
(particle) degree
暂无。