It will be some years before some foreign doctors change the impression they have ____Chinese medicine, _____, in their opinion, is nothing but raw herbs and not effective at all in treating diseases[ ]

下列句子中，没有语病的一句是

It was early morning in London _____ Prime Minister Cameron arrived to give his speech

With the rapid development of medical science, we ________ more new drugs used in the treatment of cancer

The opening between walls was very narrow; it’s very hard for soldiers to _______ through.