信号从DWDM机房到办公室电脑可使用(    )光纤。

关于投标保证金的说法，正确的是（  ）。

请阅读  Passage 1,完成第  21~25小题 。

Passage 1

First two hours, now three hours-this ishow far in advance authorities are recommending people show up to catch adomestic flight, at least at some major U.S. airports with increasingly massivesecurity lines.

Americans are willing to toleratetime-consuming security procedures in return for increased safety. The crash ofEgyptAir Flight 804, which terrorists may have downed over the Mediterranean Sea,provides another tragic reminder of why. But demanding too much of airtravelers or providing too little security in return undermines public supportfor the process. And it should: Wasted time is a drag on Americans ' economicand private lives, not to mention infuriating.

Last year, the Transportation SecurityAdministration (TSA) found in a secret check that undercover investigators wereable to sneak weapons-both fake and real-past airport security nearly everytime they tried. Enhanced security measures since then, combined with a rise inairline travel due to the improving economy and low oil prices, have resultedin long waits at major airports such as Chicago ' s O ' Hare International. Itis not yet clear how much more effective airline security has become-but thelines are obvious.

Part of the issue is that the governmentdid not anticipate the steep increase in airline travel, so the TSA is nowrushing to get new screeners on the line. Part of the issue is that airportshave only so much room for screening lanes. Another factor may be that morepeople are trying to overpack their carry-on bags to avoid checked-baggagefees, though the airlines strongly dispute this.

There is one step the TSA could take thatwould not require remodeling airports or rushing to hire: Enroll more people inthe PreCheck program. PreCheck is supposed to be a win-win for travelers andthe TSA. Passengers who pass a background check are eligible to use expectedscreening lanes. This allows the TSA to focus. on travelers who are higherrisk, saving time for everyone involved. The TSA wants to enroll 25 millionpeople in PreCheck.

Ithas not gotten anywhere close to that, and one big reason is sticker shock:Passengers must pay $85 every five years to process their background checks.Since the beginning, this price tag has been PreCheck ' s fatal flaw. Upcomingreforms might bring the price to a more reasonable level. But Congress shouldlook into doing so directly, by helping to finance PreCheck enrollment or tocut costs in other ways.

Which of the following contributes to long waits at major airports?

要求儿童使用简单的工具和辅助材料塑造某些细节部分,学会塑造人物、动物的主要特征和动作，表现出主要的情节。这些儿童泥工活动要求针对的是（     ）。

下列不属于花椒功效的是（      ）

糖尿病酮症酸中毒应用胰岛素的方法是

反映某暴露因素与疾病风险成倍数关系的最佳指标是(     )

预防酸蚀症措施中错误的是

一家银行的外汇敞口头寸如下，日元多头100，澳大利亚元多头200，英镑多头150，瑞士法郎空头120，欧元空头280。用累计总敞口头寸法计算的总外汇敞口头寸为（  ）。

与细胞坏死最密切相关的细胞器是（）。

关于施工单位的绿色施工职责，以下说法错误的是（  ）。