高血压病患者，伴变异型心绞痛，最佳降压药物为（） A.钙拮抗药 B.利尿药 C.β受

You have to leave now _________ you can catch the early bus．

A．so that

B．as soon as

C．because

D．if

张力轧制是指（）。

A．连轧后一机架秒流量大于前一机架产生的张力轧制

B．连轧前一机架秒流量大于后一机架产生的张力轧制

C．连轧秒流量相等时产生的张力

D．前三者通称为张力轧制

Consider the following descriptions of approaches used in valuing real estate: Approach 1: In this approach, the present value of after-tax cash flows are calculated based on the investor’s required rate of return before the equity portion of the investment is deducted. Approach 2: In this approach, the value of land is estimated and is added to the price that would have to be paid if a property had to be replaced. Approach 3: In this approach, an appraisal price is estimated as the discounted net operating income based on the market required rate of return. Approach 4: This approach relies on examining recent transaction prices from a group of similar properties and depends on a reasonably liquid market. List in order, from Approach 1 to Approach 4, the real estate valuation methods that correspond to each of the four valuation approaches listed above.（）

A. The discounted after-tax cash flow model, the cost method, the income method, and the sales comparison method.

B. The income method, the cost method, the sales comparison method, and the discounted after-tax cash flow model.

C. The income method, the discounted after-tax cash flow model, the sales comparison method, and the cost method.

阅读以下说明，回答问题。
[说明]
小李的婚礼上，婚庆公司和小李的家人都进行了全程录像，婚庆公司使用DV摄录机，小李的家人使用家用VHS摄录机。婚礼过后，小李把家人拍摄的VHS录像带复制给婚庆公司，要求婚庆公司把家人录像带中记录的部分内容剪辑到婚庆公司制作的婚礼DVD中去。

婚庆公司：DV摄录机具备1394接口和标准A/V端口两种信息传输接口，DV录像内容可以通过1394接口采集到计算机中，也可以通过计算机的模拟视频采集卡从A/V端口采集视频信号到计算机中。
①这两种视频采集方法的主要区别是什么
②你认为通过哪种视频采集方法得到的视频信号质量更好，请简述理由。

在电气工程上接地主要的基本种类有（）。

A、工作接地

B、保护接地

C、重复接地

D、防雷接地