必需的

A certain amount of care or pain or trouble is necessary for every man at all times .

一定程度的忧愁、痛苦或者烦恼，对于每个人都是必需的。

A certain amount of care or pain or trouble is necessary for every man at all times.

一定的忧愁、痛苦或烦恼，对每个人都是时时必需的。

A certain amount of care or pain or trouble is necessary for every man at all times .

译：1。一定程度的担忧，痛苦或者烦恼，对于每个人都是时刻必需的。

A certain amount of care or pain or trouble is necessaly for every man at all time.

一定的忧愁、痛苦或烦恼，对每个人都是时时必需的。

A certain amount of care or pain or trouble is necessary for every man all the times.

一定的忧愁、痛苦或烦恼，对每个人都是时时必需的。

Selenium is an essential trace element for human being and it has cancer-preventive properties.

硒是人体必需的微量元素，有预防癌症的作用。

Iron is an indispensable trace element which is easily deficient in human body.

铁是人体必需的和易缺乏的微量元素。

Selenium is an active center of many enzymes essential trace element selenium in the human body.

硒是多种酶的活性中心硒是人体必需的微量元素。

Manganese is an essential trace element and it is required for many ubiquitous enzymatic reactions.

锰是一种机体必需的微量元素，但过多的锰进入体内则会产生毒性作用。

The portable heat sealing device is also a necessary tool in bag sealing technology and a梥ealed transfer.

手提式塑料薄膜热合机是&袋封&技术不可缺少的工具，也是α袋封转运所必需的。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。