6. The cause of the patient's death rests a mystery.
那病人的死因仍是个迷。
同样，上述连系动词也大多可用作实意动词，翻译时应注意辨别，避免误译。这些动词在下列各句中都是实意动词：
1. If doubt remains, an X-ray study of the stomach is necessary.
如仍有怀疑，必须作胃的X线检查。
2. We must keep the operating room free from germes.
我们必须使手术室保持无菌。

(三）表示进入某种状态或获得某种性质。这类连系动词常用的有:become (成为）,grow (变成),go (变成,成为）,turn (变成），turn out (最终证明是)，get (变得,成为），come (成为），fall (变成，成为）run (变成）等。
这类连系动词用法举例：
1. Approximately 50% of children with asthma will become symptom-free before adult life.
50%左右哮喘患儿的症状会在成年前消失。
2. The patient gets tired easily and doesn't feel like eating.
病人易感疲劳，不想吃东西。
3. Besides, there are still some infections whith are so mild that they go unrecognized.
此外，还有一些感染非常轻微，以致不为人们所觉察。
上述连系动词，除become外，大都可以用作实意动词。这些动词在下列各句中都作实意动词用：
1. Today appendicitis patients treated surgically can go home within a week or so.
现在，经外科手术治疗的阑尾炎患者在一星期左右的时间内就可回家。
2. Malignant tumors grow much more rapidly than benign, ones and can cause death if not treated.
恶性肿瘤的生长要比良性肿瘤快得多，如不治疗，可以致死。
3. You must get everything ready before the operation.
你们必须在手术前把一切准备就绪。