Hãy phân tích các đặc điểm của ngành thực vật hạt kín để chứng minh rằng đây là ngành tiến hoá nhất trong giới thực vật.

b. the carbon cycle ensures living things have a source of hydrogen

i don't have a definite answer, but i would assume not based on my experiences with my friend when we both were taking a spanish course; however, it would probably still be to your benefit to look at what questions she received, just in case. a language course and a science course differ greatly, after all.