The teacher came in ,________．

If you want to try some new learning methods, you’d better select those that are ________ for yourself.

_________ the necessary equipment, the seriously wounded man had to be sent to another hospital for the operation.

l never forget those years ____ Ilived in the country with the farmers, ____ has a great effect on my life

Such a mistake could have been avoided—Unfortunately, he _______ the mistake again and again