时而的英文：
sometimes

All year she has fluctuated between optimism and despair.
全年当中她时而乐观，时而消沉。

spatial and temporal variations in the air movement are desirable for fresh environments
空气运动随空间和瞬时而变化是新鲜环境的要求。

He was by turns devout and obscene, merry and lachrymose
他时而虔诚时而淫秽，时而欢天喜地，时而凄然泪下。

Now and then
时而,不时

He alternated kindness with severity
他时而仁慈，时而严厉。

My father interchanges severity with indulgence.
我父亲时而严厉时而宽容。

Our boss alternates kindness with severity.
"我们的老板时而和蔼,时而严厉。"

My father interchanges severity with indulgence
我父亲时而严厉时而宽容。

He was a charming mixture of glum and glee.
他是一个很有魅力的人，时而忧伤时而欢笑。

The alternation of sun and snow continued for the rest of our holiday.
我们剩余的假期里依旧时而晴天时而下雪。

Sometimes it was a palpitation, sometimes a flutter; sometimes it was a sort of gasp or gurgle.
有时候是一种颤动的声音，有时候是一种拍打声音，有时候是一种喘气和咯咯的声音。

Sometimes she spoke sensibly; sometimes she rambled.
有时她讲话很有条理，有时则讲得漫无边际。

The beginning and end of strokes are sometimes square and sometimes rounded.
用笔有方有圆，或方圆兼济。

Bachelordom, sometimes, is not noble.
单身，有时不一定是贵族。

Sometimes you act like a monkey!
你的举动有时候像只猴子似的！