If a particular vaccine is produced only by one company at a single facility, there is a possibility that the supply of vaccine could grow （） if the company decides to cease production.

It can not be denied that the existing resources on ear...

单项选择题It can not be denied that the existing resources on earth will be depleted, but scientists are （） to concede the inevitability of that day,（）that new energies can be found in the near future.