液压牵引采煤机牵判部的液压系统土要中哪几部分组成？各部分的主要作用是什么？
参考答案：
液压系统主要由下列针部分组成；
（1）主油回路：由油泵与马达组成，油泵排出的油供马达做功进行牵引。
（2）补油回路：又称热交换回路，用以向主油回路补充马达工作时泄漏的油液。
（3）高压保护回路：通过高压安全阀，保护高压系统液压元件。
（4）控制回路：用于控制主油泵的排量与方向。
My name is Megan. Today I am so 1_____ as my dad is taking me on a special boat called Barada. It is a really sunny day today and dad thinks it would be a fun day to 2_____ a boat trip. I pack a bag and wait my dad by the front door. It doesn’t 3_____ much time for my dad to prepare 4_____ he needs and then we set off (出发). Once we 5_____ the boat, I’m very excited. Dad tells me to sit down as we are ready to set sail (起航). The wind is blowing6_____ my long hair when I see a black figure(人物) 7_____ to us. I’m very worried but my dad tells me 8_____ worried. But then … BANG! It is a huge whale. He hit 9____ into our boat. “Be careful, Megan!” my dad shouts, but it is too late. I fall into the water. It’s lucky 10_____ I’m not hurt and I swim to the boat and my dad helps me get on the boat.
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