what should we use (think) & (thought)?

I think she is naughter and lazy.是最正確
如果你想形容我以前認為她naughter & lazy，就應用
I thought she was naughter and lazy.
如果是填充題，就要留意前後的tense或時間用語

I think 即現在還是這麽認為。
I thought 即以前曾經認為她怎樣怎樣，暗示現在已經了解她不是那樣的了。其實 I thought 之後該用 she was ，因為她根本不是怎樣怎樣。

It doesn't matter which one you use. If you want to say about it in the past, then you use [thought]. On the other hand, you can use [think] if you just want to say in the present. By the way, is there a mistake in your sentence? Is it better to be:
I think she is naughty and lazy.
I thought she is naughty and lazy.

"I think she is naughter & lazy." is better. The tense in this sentence is simple present tense.

However, please note that the sentence is not 100% correct. I suggest it can be: "I think she is naughty and lazy."

1) there is no comparison existed - "naughter" should not be used.
2) the spelling is not correct - "naughter" should be "naughtier"
3) the sentence is not consistant - you should use "-er" for both adjectives or no "-er" for both.

I think she is naughter & lazy.