基本上,-ing短语放在句尾是修饰邻近的动词的,所以using a Doppler ultrasound device修饰的是be detected,逻辑主语是所修饰动词的逻辑主语。
B中分词短语using a Doppler ultrasound device逻辑主语是fetal heartbeat,fetal heartbeat不能using...所以错误
D中using a Doppler ultrasound device应该跟在它所修饰的名词后面,即By the twelfth week of pregnancy, fetal heartbeats can be detected by a physician using a Doppler ultrasound device
基本上,-ing短语放在句尾是修饰邻近的动词的,所以using a Doppler ultrasounddevice修饰的是be detected,逻辑主语是所修饰动词的逻辑主语。
B中分词短语using a Doppler ultrasounddevice逻辑主语是fetal heartbeat,fetal heartbeat不能using...所以错误
D中using a Doppler ultrasound device应该跟在它所修饰的名词后面,即By the twelfth week of pregnancy, fetal heartbeats can be detected by a physician using a Doppler ultrasound device
那也就是说D中using a Doppler ultrasound device是做定语修饰名词而不是做状语修饰动词?