VOA慢速英语:New Treatment for AIDS Called a ‘Big Deal’

短语讲解：

1. We've now gone to -- with six doses that were capable of infecting control ((untreated)) animals -- we've gone to 16 times that."

be capable of 能够
例句：Be ready to assemble at the first call and be capable of fighting and winning. 
召之即来，来之能战，战之能胜。 

2. But experimental AIDS vaccines fail at this because the virus is always mutating, or changing, to avoid destruction. HIV and SIV are both able to do this because of a surface protein that mutates to avoid the body’s immune system.

because of 由于
例句：It was very difficult to see our way because of the fog. 
由于有雾, 我们很难看清道路。 

3. Because HIV is sort of fooled into thinking that it's binding the cell, it undergoes the changes that it would normally do when it's ready to enter a cell

be ready to 预备，即将; 甘于; 肯; 乐意
例句：You should be ready to solve any problem that may come along. 
你应该随时准备解决可能出现的问题。