John is very tall, so he is easy to ________ in the crowd.

If you keep working like this, your health will ________ under the pressure of work sooner or later. [ ]

I go to school ______ my father’s bikeevery day.

Liu Tao is good at all the subjects at school, _______ English.

Recently the Ministry of Environmental Protection issued a circular saying that China may adopt flexible working hours and stop school classes_____the highest air pollution warnings.