开心

happy; joyful; glad; delighted; pleased; elated; cheerful; merry; overjoyed; thrilled; joyous; feel happy; joy; delight; pleasure; amuse; rejoice; make fun of; tickle; happiness; cheerfulness; amusement; mirth; gladness; happily; joyfully; cheerfully; with pleasure; with delight

一下

one time; once; stroke; all of a sudden; in a short while; in one go; at a single stroke sudden