Even when textbooks are standardized throughout a school system, methods of teaching with may be greatly varied.
Giải chi tiết:
Đáp án là A. standardized: được chuẩn hóa >< different: tách ra, khác rõ rệt
Các từ còn lại: made the same : làm giống; expensive: đắt; lacking : thiếu
Population growth rates vary among regions and even among countries within the same region.
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.