引起射线照相底片黑度过高的两种原因是（）A、过度显影与水洗不足 B、过度显影与过度定
题型：单项选择题
问题：
引起射线照相底片黑度过高的两种原因是（）
A、过度显影与水洗不足
B、过度显影与过度定影
C、过度曝光与过度定影
D、过度曝光与过度显影
题型：单项选择题
Reading comprehension
Potatoes are very popular today. But in the past this was not true. Potatoes grew in South America 5,000 years ago. But they only became popular in other places 200 years ago.
In the 16th century, the Spanish took the potato from South America to Europe. But the people
didn't like this strange vegetable. Some people thought that their skins would look like the skin of the
plant if they ate the potato. So they only ate the leaves. This made them sick because there is poison
(毒药) in the leaves.
In the 1800s, people started to eat potatoes. Potatoes became the main food in Ireland. Then
something unlucky happened. In 1845, a disease killed all the potatoes in Ireland. Two million people
died of hunger.
Today each country has its potato dish. Germans eat potato salad, and the USA has the baked
potato. Of course, the French invented French fries.
Fill in the blanks according to the passage. Only one word for each blank.
Potatoes were 1 in South America 5,000 years ago. But they weren't popular in other places 2
200 y
ears ago. In the 16th century, the Spanish took them to Europe. They ate leaves 3 of having
potatoes. As a result, people were badly ill because of the poison in the leaves. In the 1800s, people
started to eat potatoes. 4 , there was something wrong with the potatoes. Two million people died
because of the shortage (缺少) of potatoes in 1845. But now there are many 5 of potato dishes in
the world.
