________they visited the Science Museum,
题型：选择题
问题：
________they visited the Science Museum, they showed great interest in everything they saw. [ ]
A. The first time
B. For the first time
C. At first
D. At the first time
________they visited the Science Museum, they showed great interest in everything they saw. [ ]
A. The first time
B. For the first time
C. At first
D. At the first time