必须

Equipment used in oxygen service must meet stringent cleaning requirements; any system must be construct ed of materials that have high ignition temperatures and which are nonreactive with oxygen under the service conditions.

氧气设施中使用的设备必须满足严格的清洁要求；系统必须采用具有高点火温度且在使用条件下同氧不反应的材料建造。

Equipment used in oxygen service must meet stringent cleaning requirements; any system must be constructed of materials that have high ignition temperatures and whichare nonreactive with oxygen under the service conditions.

氧气设施中使用的设备必须满足严格的清洁要求；系统必须采用具有高点火温度且在使用条件下同氧不反应的材料建造。

The scientific understanding is the basis of correct judicial authentication conclusions, while nonscientific understanding brings wrong ones inevitably.

保障鉴定人认识活动的公正性，一方面必须完善管理规范和职业道德规范，另一方面必须建立规范鉴定行为的法律制度和"证实"与"证伪"的法律措施。

To build these skills, lifelong learning must become normality, and three main barriers have to be overcome.

为了培养这些技能，终身学习必须成为常态，三个主要的训练参与障碍也必须加以克服。

It is in mind as in body which must be nourished by good food.

精神和身体都必须有好的食物精神和身体都必须有好的食物来营养。

In some you have to move fast and avoid foes while in others you have to actually obliterate them.

在一些你必须迅速行动，并避免政敌而在其他国家，你必须实际上是抹杀他们。

If two parties want to sign a contract C over a communication network, they must "simultaneously" exchange their commitments to C Since simultaneous exchange is usually impossible in practice, protocols are needed to approximate simultaneity by exchange partial commitments in a piece by piece manner The party of secondly sending commitments may have a slight advantage; a "fair" protocol must keep this advantage within acceptable limits The protocol for signing a contract is improved based on the research result of secure multiparty computation In this protocol, the parties obliviously transfer the signed bit and the committed bit; the other parties can prove the validity of this bit based on the confirming sub protocol, but he cant gain more information about the whole signature by accumulating the signed bit or the committed bit After the parties exchange the whole signed information, they declare the commitment about the signature respectively, and gain the whole signature of the other party At this moment, the party doesnt care about the advance quit of the other party, because he has gained the whole signed information Finally, it is proved that this protocol is quit fairness

在网络环境中解决合同签订问题需要保证信息交换的同时性，以前提出的协议都会给第 2个发送者部分计算特权，利用不经意传输协议则可以解决这个问题在协议执行过程中，参与者将合同的签名位以及他对签名位的承诺不经意传输给对方，对方可以利用验证子协议证明该位的有效性，但是他却不能通过位交换次数的增加获取更多的完整签名的信息；在完成签名位的交换之后，参与者分别宣布承诺，并得到对方对合同的完整签名；在宣布承诺时，协议参与者已经获得全部的签名内容，要么是签名位，要么是对方对该位的承诺，因此参与者并不需要担心对方提前终止协议在文章的最后利用多方安全计算的结论证明了该协议满足终止公平性1 引言两个参与者A和B想要通过网络协商签订合同C 为了保证公平性，参与者必须同时交换自己对合同的签名，然而在实际的网络环境中，想要完全同时地交换对合同的签名是不可能的，他们必须将签名分成若干块依次地执行，以保证大致的同时性但是这种方法依然存在着问题

The consignor must furnish such information and attach to the air waybill such documents as are necessary to meet the formalities of customs, octroi or police before the goods can be delivered to the consignee.

托运人必须提供必要的资料并在航空货运单上附上此种文件，以便在货物交付收货人以前必须完成的海关、税务或公安手续。

According to Faraday's experiment, there must be a wire testing the existence of the electric field, just as there must be a magnetic pole, or needle, testing the existence of a magnetic field in Oersted's experiment.

根据法拉第的实验，必须有导线来检验电场是否存在，正像在奥斯特的实验中也必须有磁极或磁针来检验磁场是否存在一样。

It must be communicated to the offeree and must clearly undertake a performance definite as to all essential terms.

报盘必须有明确的受盘人，报盘的所有主要内容必须十分确定。

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％。