Although the turtle has been toothless for more than 150 million years, in some contemporary turtle species the moderately sharp and jagged edges of their horny jaws function for teeth.
Although the turtle has been toothless for more than 150 million years, in some contemporary turtle species the moderately sharp and jagged edges of their horny jaws function for teeth.
their horny jaws function for teeth
its horny jaws function for teeth
its horny jaws function as do teeth
the horny jaws function as teeth do
the horny jaws function as teeth 选E。说DO无法指虚词,但不知有什么更好的解释呢。 我只是觉得有DO语义表达更清楚。