When you turned the sentences of Application 6 into questions or negative statements, you split the verbs between the first auxiliary and the rest of the verb string. But what happens when the verb is a single word? You have to change a single-word verb to a verb string before you can split it. For this purpose, add the auxiliary do, does, or did. Then split the string to make the question or negative statement:
Those people train tigers. -- Those people do train tigers.
Question: Do those people train tigers?
Negative: Those people do not train tigers.
Sandra trains tigers. -- Sandra does train tigers.
Question: Does Sandra train tigers?
Negative: Sandra does not train tigers.
Sandra trained tigers several years ago. -- Sandra did train tigers several years ago.
Question: Did Sandra train tigers several years ago?
Negative: Sandra did not train tigers several years ago.
Notice that if the single-word verb ends in -s or -ed, it drops that ending as it enters the verb string, allowing the auxiliary to show the time clues. Chapters 9 and 10 explain this shift. For now, practice adding do, does, or did and then splitting the new verb string.
Tip for finding verbs: Turn each sentence into a negative statement. The word not will come before the main verb and after any auxiliaries. (When a form of the verb to be stands alone as a single-word verb, it is an exception; it will come right before the word not.)
The verb to be often behaves differently from other verbs. When a form of to be stands alone as a single word verb, it doesn't need to split to form a question or a negative statement. It simply moves to the beginning for a question, or adds not for a negative statement:
Dinosaurs were warm-blooded. Were dinosaurs warm-blooded?
Their bones are like birds' bones. Their bones are not like birds' bones.