It ___(rain) now. It ____(begin) raining two hours ago. So, it ________(rain) for two hours.

Sure, here is the step-by-step response:

1. Identify the tense required for each blank:

   • The first blank describes an action happening right now.
   • The second blank describes an action that started in the past.
   • The third blank describes an action that started in the past and is still continuing.

2. Fill in the blanks with the appropriate verb forms:

   • For the first blank, use the present continuous tense.
   • For the second blank, use the past simple tense.
   • For the third blank, use the present perfect continuous tense.

3. Complete the sentence:

   • "It is raining now. It began raining two hours ago. So, it has been raining for two hours."