不得而知: unknown, unable to find out...
相同: identical, same...
吸烟: to smoke...
大姐: big sister, elder sister, older sister (also polite term of address for a girl or woman slightly older than the speaker)...
流量: flow rate, rate, throughput, site traffic (Internet)...
由来: origin...
不为人知: not known to anyone, secret, unknown...
干事: administrator, executive secretary...
任重道远: a heavy load and a long road, to bear heavy responsibilities through a long struggle...
测验: test, to test...
