题干

某同学用显微镜观察自制的血涂片,请根据所学知识回答以下问题:

(1)图(一)中的A、B、C 是视野中观察到的三种血细胞,其中能保护身体抵抗细菌等侵袭的是____ ,煤气中毒是因为CO与其中的____ 细胞上的血红蛋白牢固结合所致(两空格均填图中字母).

(2)如果图(一)是低倍镜下的观察图象,现在该同学想进一步用高倍镜观察图(一)中的A的结构图象,你认为他最先要做的一步是____ 

(3)图(二)是用显微镜观察装片时常见的两种情况,你认为Ⅰ和Ⅱ两种情况下,视野较暗的是____ .

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答案(点此获取答案解析)

A,C,往左上方移动玻片,I

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根据短文理解,选择正确答案。

7 January, 2014

    A new report says more and more international students are attending colleges and universities in the United States. It also notes a large increase in the number of international students from China.

    These findings are from the latest Open Doors Report. The report documents the record number of international students in the United States during 2012, 2013 school year. It says more than seven hundred sixty-four thousand four-hundred such students were attending American colleges and universities during the last two years. That represents an increase of almost six percent than one year earlier. On the other hand, the number of Americans studying overseas(海外) increased by one percent, which reached nineteen thousand this year.

    The report says one hundred ninety-four thousand students at American colleges and universities were from China .That is an increase of more than twenty-three percent over the year before. Peggy Blumenthal, an expert(专家)of international education, described the effect of the increase in Chinesestudents.

    "Now they have been coming for some time. But this year was the highest level ever." She says many Chinese families are able to pay for the highest-quality education for their children. The children mainly choose to study in America.

    "We know many of them have enough income to be able to afford to send them anywhere in the world if they want to go. And for the most part, looking around the world, Chinese students still prefer to come to the United States as their choice."

    Chinese students are not the only ones who want to attend American colleges and universities. After China, India sends the second largest number of students to the United States for higher education. India has about one hundred thousand students in American schools. South Korea is third with about seventy-two thousand students.

    Why do so many foreign students study in the United States? Peggy Blumenthal provides one reason.

    "The advantage America has is that we have a huge system (系统)and a very perfect system. So there are over four thousand universities and colleges in the United States. Among them are some top ones in the world, and what that tells us is there is still a lot of room to host international students.

    Foreign students represent less than four percent of the total student population in American higher education. And from Learning English, that's the VOA Special English Education Report. I'm Bob Doughty. Thanks for listening.