一道SAT的语法题New Zealand had fostered a thriving local music sce

...it was not until the late 1980s ( ) New Zealand musicians began to reach international audiences.
这个空格应该填that,因为" It was...that..."是强调句,本句强调了“not until the late 1980s”.
不强调的话,应为New Zealand musicians did not begin to reach international audiences until the late 1980s.