单项选择题 以下哪些不是交流传动技术的优点 A、功率因数高 B、电机体积、重量小 C、控制技术简单 D、电制动能量可以回馈电网

单项选择题 不属于法洛四联症畸形组成的是 A、肺动脉狭窄 B、室间隔缺损 C、主动脉骑跨 D、右心室肥大 E、房间隔缺损

未知题型 听力原文： The train I was traveling on was already half an hour latE.I had planned to arrive in Chicago at 7:00 in time to catch the 7:50 train to St. Louis, but there was no hope of that now. I explained the situation to the conductor who advised me to get off before Union Station and take a taxi. When the time came, he even helped me with my languagE.He wished mea good luck as I jumped off, and a few minutes later I was going towards the Union Station in a taxi. It was almost 7:50 when we stopped outside the station, I paid the driver quickly, carried my bags and hurried insidE.'The St. Louis train....'?' was all I had time to say to the first porter I saw. You can imagine my disappointment when he pointed to a train that was just moving out of the station.When did the train he was travelling on arrive in Chicago?A.At 7:00.B.At 7:50.C.In timE.D.Behind its timE.