Jack was very lazy. He did no work and spent most of the time playing video games. As a result, he failed the exam.
Giải chi tiết:
Biogas can be utilized for electricity production, cooking, space heating, water heating and process heating.
Around 150 B.C. the Greek astronomer Hipparchus developed a system to classify stars according to brightness.
Population growth rates vary among regions and even among countries within the same region.