Boys in early adolescence are not _________ to the cinema because the film is not suitable for them.

He is really like a gentleman and he usually          the door open to let the ladies go first.

One way for students to prevent H7N9 flu virus is to open the windows of the classroom to allow the air to ________.

The old man is ________ enough to contribute $ 10,000 to the disaster area damaged by the earthquake.

The invention of steam engine greatly sped up the industrial revolution, which ________ a lot to the take-off of the world.