Why are sub-saharan rivers not very useful for travel?

The tea bush grows best in east asia’s zones.a) arid and semi-arid.b) arid and tropical .c) tropical and subtropical.d) humid continental and subtropical.

The 5th term in a series of even number that begin 3x

Why have the countries of the region had difficulty establishing democratic governments in recent years? choose all answers that are correct b is also correct i need to know if theres any morecommunists have overtaken the countries of the caucasus region. the soviets established national borders in the region without considering the location of ethnic groups. fighting continues between armenia and azerbaijan over the nagorno-karabakh region. civil war between communists and islamic groups in tajikistan resulted in thousands of deaths and refugees are forced to flee. in a test!