The most suitable option for the first question is definitely <span>stratus clouds which usually stratch over the sky creating overcasts.
The next one should be </span><span>nimbus, as they dark and usually help to predict the storm.
And the last one </span>cumulonimbus that point on thunderstorms and so on.
Human chorionic gonadotropin (hCG) is secrete by the embryo early in pregnancy to keep the corpus luteum for dying. This positive feedback will maintain the corpus luteum, which secretes Progesterone and Estrogens throughout pregnancy, in order to keep the endometrium well to nourish the embryo/fetus.
