单选题 Emoticons and emojis, for example, may not be appropriate where a more formal ____ is required.

单选题 It amounts to little more than a drop in the bucket of what is needed if we are to make full use of this ____ resource.

单选题 With so much to learn about life in the depths of the ocean it is surprising there is so little ____ for deep sea exploration.

单选题 We have spent a great deal of time and money exploring space, but remain ignorant about vast areas of our own ____.

单选题 For we still know little of the world ____ the seas.

单选题 With so much to ____ life in the depths of the ocean it is surprising there is so little funding for deep sea exploration.

单选题 It amounts to little more than ____ of what is needed if we are to make full use of this vital resource.

单选题 We have spent a great deal of time and money ____ space, but remain ignorant about vast areas of our own planet.

单选题 Given our growing population the oceans may even hold the key to the ____ of our species.