— Come on! You could recite (背诵) the long poem ____ difficulty.         

— Thanks. I've learned it _____ heart.     

    Rock climbing is a popular hobby that many people enjoy doing. You can do it indoors on special walls or outdoors on real mountains. There are many advantages of rock climbing—it is fun and it also helps people forget worries.

    The most important equipment(装备)to have is good shoes. They need to be half a size smaller than your usual size. The next thing you need is a harness(保护带).This allows you to move freely, but will hold you up if you fall. It's important to know how to use your equipment. Otherwise, it may be dangerous. If you are a beginner, it's best to have lessons. A climber with experience can help you a lot in the beginning.

    Rock climbing is very exciting for people of different ages. Climbers, however, must be careful not to pollute the environment. Sometimes rock climbers leave rubbish on the mountains where they climb. They should take it with them and throw it away. This will allow future climbers to enjoy a clean environment.

若一个圆锥的底面圆半径为3cm，其侧面展开图的圆心角为120°，则圆锥的母线长是____cm．

读 《有的人》,"名字比尸首烂得更早"与诗中的____呼应对称。