以免：（连词）用在下半句话的开头，表示目的是使下文所说的情况不至于发生
in order to avoid; so as not to; lest
e.g. 工地上应该加强安全措施，以免发生工伤事故。
Safety measures should be tightened up on the work-site to avoid injuries.
e.g. 借阅的书籍应该在限期之内归还，以免妨碍流通。
The borrowed books should be returned within the time limit in order not to hinder the circulation.
