Помогите! Срочно! Англ. яз. підкресліть у кожному з них модальне дієслово або його еквівалент. Перекладіть речення

1.The earliest man could not measure or count at all.
2.He has spent some years on this experiments, so the results obtained may be trusted.
3.To make the air hot enough, the Diesel engine has to use higher pres sure than the petrol engine.
4.Some types of space suits can only be used for short trips into space being limited by air and oxygen supplies.