题目

下面是四个化学反应，你认为理论上不可用于设计原电池的化学反应是 A．Zn＋Ag2O＋H2O==Zn(OH)2＋2Ag           B．Pb＋PbO2＋2H2SO4==2PbSO4＋2H2O  C．Zn＋CuSO4==Cu＋ZnSO4                 D．CaO＋SiO2CaSiO3 答案：DLakes, ponds, and beaches mean summer fun and cool relaxation from hot weather. But water also can be dangerous for kids if you don't take great care. Nearly 1,000 kids die each year by drowning. Here are some tips to keep your kids safe in the water: At the Lake or Pond ·Don't let little kids swim alone without adult supervision— lakes or ponds may be shallow near the bank and are suddenly deep sharply further out from shore. ·Ponds and lakes may hide jagged rocks, broken glass, or rubbish. ·Make sure kids wear foot protection; even in the water, they should wear socks or water shoes. ·Watch out for weeds and grass in the water that could trap a leg or arm. ·Most boating accidents, particularly among teenagers, are related to alcohol(饮酒). Be sure teens know about the dangers of alcohol, on and off the water. At the Beach ·Teach kids to always swim when and where a lifeguard is on duty. Unlike the calm waters of a swimming pool, the beach has special dangers like currents and tides(暗流). Check with the lifeguard when you arrive to find out about the water conditions. ·Tell kids never to stand with their back to the water because a sudden wave can easily knock a child over. ·Teach kids that if they're caught in a dangerous wave, they should swim parallel（顺行地） to the shore or should tread （踩）water and call for a lifeguard's help. Whether at the lake or at the beach, teach your child to get out of the water during bad weather, especially lightning. 1.Which is the right behavior when swimming at the beach? A. Go off the water without a lifeguard on duty B. Go on swimming in a heavy rain C. Go off the water after checking the water conditions D. Call for help if caught in a dangerous wave 2.A child should_________ at a lake. A. swim on his/her own           B. be careful about weeds and grass C. swim without shoes on         D. drink only a little wine 3.Swimming at a beach is more dangerous than in a pool because          . A. there are no lifeguards at a beach     B. there are currents and tides at a beach C. the waters of a beach are more calm.  D. the waters of a pool are warmer 4.The passage is probably written for          . A. students at school              B. kids who want to learn swimming C. parents with little children       D. coaches who teach kids to swim 5.In which column(栏目) of a magazine can you find this passage? A. Education     B. Science     C. Entertainment       D. Sports