Objective To determine the persistence of immune protection of China-made, plasma-derived hepatitis B vaccine in infants and the time table of booster immunization.

目的确定国产乙肝血源疫苗低剂量免疫保护持久性及用重组酵母乙肝疫苗加强免疫的免疫应答。

youdao

To be sure it reaches the necessary speeds, the X-43A will be attached to a booster rocket and ride piggy back on a B-52 to 24, 000 feet.

BBC: Mach 10 scramjet prepares for launch

B-52 bomber, dropped from the bomber, and then accelerated to Mach 7 by a booster rocket.

ECONOMIST: Hypersonic aviation