With a lot of difficult problems ________, the manager felt worried all the time.
A:settled
B:to be settled
C:settling
D:to settle
断开1mol H一H键、1mol N一H键、1mol N≡N 键分别需要吸收能量为436kJ、391kJ、946kJ,求:H2与N2反应生成0.5molNH3填____ (“吸收”或“放出”)能量____ kJ.
下列句子中没有语病的一项是( )