Medical researchers are painfully aware that there are many problems ______________ (他们至今还没有答案)
点评：本題要翻译成英语的`定语从句，修饰前面的problems，时态最好用现在完成时，故可翻译成：(which / that ) they have not come up with / found a solution to.
__________（大多数父母所关心的）is providing the best education possible for their children.
点评：本句的汉语部分要翻译成英语中的主语从句，宜用what引导，可翻译成What concerns most parents 或者What most parents are concerned about。
Youb better take a sweater with you ________(以防天气冷).
点评：本题重点考察以防，可以翻译成in case引起的从句，从句中的谓语动词多用should+动词原形，但可以不用虚拟语气，而用动词的陈述语气。所以，本题可翻译成in case it turns / becomes cold.或者in case it should turn / become cold.
Through the project, many people have received training and _______(决定自己创业).
点评：本题重点考察创业，可翻译成to launch / set up / establish / begin their own enterprise. 或者to launch / set up / establish / begin an enterprise of their own.
The anti-virus agent was not known _________ (直到一名医生偶然发现了它)
