Suppose that we have two coins C1 and C2. The probability of C1 having head is 0.6, and the probability of C2 having head is 0.4. In each test, we toss both coins, and read the faces of C1 and C2 (note that we read C2 after reading C1). For example, if the toss resulted in C1 head up and C2 tail up, we will record the result as HT. Suppose we perform the test 4 times. What is the probability for us to observe the following result?

HT, HT, TT, TT?