我看书，看了一个钟头 is the most common way。PS： you also can say 我看了一个小时（钟头）的书。

the first and the second sentences are right. the third answer is wrong. But there is another native saying:我读了一小时的书。 the translation of read：看 is okay, but 读 is better.

你好，我又来了。哈哈 Duration of action with verb+object is a very common expression in Chinese. If the action is already done，we have two options，please try to find the rule by yourslef first. 我上了一个小时课。/我上课上了一个小时。 我看了半天书。/我看书看了半天。 我学了一年汉语。/我学汉语学了一年。 Yes，you are right. The first structure is S+V+了+Duration + O. The second structure is repeating the verb，S+V+O+V+了+Duration. Meaning to use the basic structure SVO first then repeat the verb with duration. No matter what，the duration should be always together with V+了. This is the use of daration complement，the key is to get the right order of complement and object. If you want to express the action you are going to do in the future，just remove 了， and add a 要 before verb. I believe this can help you.

我看书，看了一个钟头。一个钟头more colloquial. 我看书，看了一个小时。 use in writting . or 我书看了一个小时。