Why was China able to stay isolated from the world for so long? i have a china test and this is the review and its confusing-

Choose one of these concerns and write a short paragraph about its impact on africa. what has caused this problem to occur, and how has it impacted people who live there?

When the communist, under mao, took control of china in 1949 they announced total support support for which country and its ideology?

Donald is studying the eating habits of all students attending his school. he samples the population by dividing the students into groups by grade level and randomly selecting a proportionate number of students from each group. he then collects data from the sample. which type of sampling is used? select the correct answer below: systematic sampling convenience sampling stratified sampling cluster sampling