【单选题】下列命题中,正确的是
B.
命题“ 为真”是命题“ 为真”的必要不充分条件
【单选题】Which sign can you probably see in the library?
【单选题】Which sign means you can't turn left? [ ]
【单选题】Which sign can you mostly see in the school library?
【单选题】Which of the following words can NOT be used to complete 'This is the place ______ I visited'?
【单选题】下列命题中,正确的是
C.
命题“ 为真”是命题“ 为真”的必要不充分条件
【简答题】下列命题中不正确的为 A上升气速过大会引起漏液 B 上升气速过大会引起液泛 C上升气速过大会使塔板效率下降 D 上升