1. Many times online students will not always be right; they just need to be prepared to accept a challenge.
    7. 跟上课程进度。

2. Cloning is a radical challenge to the most fundamental laws of biology, so it's reasonable to be concerned that it might be a preface to activities that will threaten human society and dignity.
    克隆向生物学最基本的规律发起了一次革命性的挑战，因此有理由担心这或许是威胁人类社会和人类尊严的活动的序曲。

3. Roses Only is a good example of a discount rose retailer that was transformed from a traditional shop to answer the challenge in the '90s.
    "惟一玫瑰"是90年代从传统花店转变为折价玫瑰花零售店以应对挑战的一个成功范例。

4. Old stockings have always been perceived as a challenge by my family.
    旧长筒袜在我家一直都被视为一种大有可为的东西。

5. Leonardo Da Vinci, who lived in Italy during the fifteenth century, enjoyed every possible challenge.
    里奥纳多·达·芬奇生活在十五世纪的意大利，他喜欢各种可能的挑战。

6. For instance, Alex Au, a Stanford Ph. D. from Hong Kong, has set up a Taiwan factory to challenge Japan´s near lock on the memory-chip market.
    比如说，亚历克斯.奥，一位来自香港的斯坦福大学博士，已经在台湾建厂，对日本在内存条市场上近似垄断的局面提出了挑战。