问题
单项选择题
黑血法的错误概念是（）
A.是预饱和血管成像技术
B.可以显示脑组织中的黑核、红核
C.利用预饱和脉冲使流体和固定组织加以区别
D.预饱和技术可以成功的选择性去除动脉或静脉
E.进入层面未经预饱和的血液呈黑色
答案
参考答案：E
解析：通过预饱和技术使图像中流动的血流呈黑色低信号，称黑血技术，可以用来辨认血流方向、鉴别流动的血流与静止的血栓。
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黑血法的错误概念是（）
A.是预饱和血管成像技术
B.可以显示脑组织中的黑核、红核
C.利用预饱和脉冲使流体和固定组织加以区别
D.预饱和技术可以成功的选择性去除动脉或静脉
E.进入层面未经预饱和的血液呈黑色
参考答案：E
解析：通过预饱和技术使图像中流动的血流呈黑色低信号，称黑血技术，可以用来辨认血流方向、鉴别流动的血流与静止的血栓。
| The safety of ships at sea does not depend only on the arrangements made in the ships themselves. Dangerous coasts and rocks may be seen in the daytime, (51) they are a threat to safe navigation at night. Lighthouses are therefore erected at such places to (52) sailors of the danger. Modern lighthouses are put up at all dangerous places near the courses (53) by ships. On some rocky coasts several lighthouses may be built not far from each other, and (54) the sailors on a ship may know which is which, they have (55) arrangements of lights. One lighthouse will give a single flash at regular (56) , another may give two flashes; a third may give two followed by one; and so on. (57) watching the lights the navigator is able to decide exactly where he is, and he can set his (58) with confidence. In the approaches to some ports two continuous lights are set up, one above (59) but some distance behind; when they appear from the sea one above the other, the ship is on the right course; but if they do not, the captain knows that he is (60) his course and likely to strike a rock or the bottom of the sea. |
A．explored
B．passed
C．constructed
D．followed