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【单选题】
俗话说：“千年琥珀万年蜡”，其实，琥珀、蜜蜡的年龄要得多，一般在 年之上。琥珀是新生代第三纪地球上松柏科植物分泌的树脂，随着地质作用而掩深埋，经过长期的地质时期，聚合、固化形成琥珀。A.
2000-3000 万
B.
3000-4000 万
C.
4000-5000 万
D.
5000-6000 万
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举一反三
【简答题】简述 减弱电离层影响的措施。
【单选题】听力原文： I was a teacher. My home was not far from my school, and l always walked there in the morning. All the pupils in the school were very young. I walked to school on a very cold and windy morning i...
A.
a long way
B.
far away
C.
not far
【单选题】My teacher told me seriously that I should keep ______of that fellow who always caused troubles.
A.
clean
B.
cleanly
C.
clear
D.
clearly
【单选题】I feel it hard to keep up with my classmates. But whenever I want to ______, my teacher always encourages me to work harder. [ ]
A.
go on
B.
give up
C.
run away
D.
give back
【简答题】淀粉水解试验主要是检测细菌是否能够产生____,使淀粉水解为麦芽糖和葡萄糖,根据淀粉遇碘变蓝的特性检测淀粉是否被水解。
【单选题】I felt it hard to keep up with my classmates. But when ever l want to________, my teacher always encourages me to work harder. [ ]
A.
go on
B.
give up
C.
run away
D.
give back
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