LES计分时，长期性事件影响时间的计分如果在半年内记为（）次。
A.1
B.2
C.3
D.4
参考答案：B
The dictionary isn't expensive but it is __________. [ ]
A. great significance
B. for great significance
C. of great significance
D. of great significant
投密封油备用油源时，高、低压备用油源间联络门处于何种状态？为什么？
