【C18】A．fieldB．courtC．ringD．ground

The main point of paragraph 5 is ______.A．to describe the existing research in the fieldB．

Grounded whales often struggle fruitlessly to reenter deep water.A．violentlyB．desperatelyC

Intemet使用的协议是A．X.25／X.75B．TCP／IPC．Token RingD．CSMA／CD

Which of the following is NOT a variable of register according to Halliday？A．FieldB．TenorC

A Doppler speed log indicates speed over ground _

A．excuseB．justificationC．causeD．ground