园林树木壮年期后期，应对生长势衰弱的外围枝条（）以调节树势，切断部分骨干根以进行（），防止早衰。
参考答案：短截更新；根系更新
Questions 17 to 20 are based on the following passage. At the end of the passage, you will be given 20 seconds to answer the questions. Now listen to the passage.
Why was the speed limit first reduced to 55 miles-per-hour
A．The older people wanted it.
B．The voters decided on it.
C．It was decided that speeds above that were not safe.
D．The US had a fuel crisis.
承运人甲按照托运人乙的要求将一批杨梅运到杭州市，但到达指定地点后没有找到收货人。原来乙填写地址错误，后甲又按照新的地址将货物运到收货人丙处，但因为行程耽搁，部分杨梅已经腐烂。该腐烂的杨梅的损失应由( )承担
A．承运人甲
B．托运人乙
C．收货人丙
D．托运人乙和承运人甲共同承担
