Mary prefers not to be on a diet.

The doctor said that I should be on a diet.

医生说我必须节食.

The couple seemed to be on cloud nine.

那对夫妇看上去极其幸福.

Tokyo's trains and metros meet thousands upon thousands people to be on duty and off duty.

东京的火车和地铁每天接送成千上万的上下班.

Jack was on duty yesterday. He will be on duty again next month.

杰克昨天值过日. 他下个月在值日.

Under special conditions, the company will require staffs be on duty during holidays.

于特别情况下, 员工必需应公司之要求在假日出勤.

Sometimes he has be on duty at night.

有时他会在夜间值班.

Today it's my turn to be on duty.

今天该我值日.

Who will be on duty tomorrow?

明天谁值班?

Who will be on duty tonight?

今晚的夜班谁当值?

Who will be on duty at six o'clock? --- I will.

6点钟谁值班? - 我值班.

I can't be on duty tonight, would you please take my place?

今晚我不能出乘了, 麻烦你替我一次好 吗 ?

I'd love to come. But I have to be on duty this weekend night.

我是想过来, 但我周末晚上得值班.

Experienced banquet waiters must also be on duty.

还必须让有经验的宴会服务员当班.

The mountains appear to be on fire as they peer up at the drifting clouds.

云过之处群山红似火,而夏季的炎热更是火气冲天.

Doctor my whole body seems to be on fire , I don't know what to do.

医生,我整个身体都火辣辣的, 该怎么办啊!

Oh, then your barn must be on fire.

哦, 那么,也许是你家的牛棚着火了.

When I held up my hand , it , too, seemed be on fire.

我抬起手来时, 手似乎也着火了.

But at the theater my brain still seemed to be on fire.

但是晚上到了剧院之后,我的脑子还是像火烧一样.

Look at that smoke, That building must be on fire.

看那些烟, 那幢大楼一定是失火了.

Her head appears to be on fire but that is only a trick of the light.

她的头部看上去像是着火了，但那只是灯光造成的幻觉。