ⅰ.单词拼写 1．if you m________ four by five，the answer is twenty. 2．i have in mind some doubts which really p______ me. 3．most scientists believe that water doesn't e________on the surface of the moon. 4．freezing winter is h________ to orange trees. 5．plants can absorb carbon dioxide and release o________. 6．there are many ________(理论) about the origin of life.
