Section B
Directions: In this section, you will hear 3 short passages. At the end of each passage, you will hear some questions. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A, B, C and D.
听力原文: If you seize the stem of a nettle (荨麻) firmly, perhaps with the idea of uprooting a weed that is growing where it should not, you will probably feel a sharp sting in your palm or through the thicker part of your fingers. The stinging hairs on a nettle's stem are small but effective. It is not unusual to feel the sting for several hours after you touch the nettle. Long ago, when people made such lore part of their general knowledge, it was believed that you might rub the root of the nettle on the injury and the sting would disappear.
The slender nettle, Urtica gracilis, is a wayside plant growing in moist soil over a wide area. It is more sparingly decorated with stinging hairs than the stinging nettle, U. dioica. Once full grown, the slender nettle may be quite safe to handle. The pliable young stems are more likely to be protected with stinging hairs than the stems of older plants.
The American Indians found the nettle a useful plant. The fiber of the nettle is strong, and when spun together in several strands, it could be used to make twine for hobbling horses or weaving cloth.
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A.The stem of the nettle.
B.Small stinging hairs on the nettle's stem.
C.The sap of the nettle.
D.The slender nettle.
第4题
A.cAMP信号转导途径
B.胞内受体介导的信号转导途径
C.Ca2+信号转导途径
D.DAG/IP3信号转导途径
E.PI-3K-AKT信号通路
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