So difficult _____ it to adjust to an English-speaking environment that he determined to learn English hard.

1. A.
   he has felt
2. B.
   has he felt
3. C.
   he did feel
4. D.
   did he feel

 So difficult _____ it to adjust to an English-speaking environment that he determined to learn English hard.

A. he has felt         B. has he felt         C. he did feel         D. did he feel

So difficult _____ it to adjust to an English-speaking environment that he determined to learn English hard.

A. he has felt         B. has he felt         C. he did feel         D. did he feel

So difficult _____ it to adjust to an English-speaking environment that he determined to learn English hard．

A．he has felt        B．has he felt         C．he did feel          D．did he feel

So difficult _____ it to adjust to an English-speaking environment that he determined to learn English hard．

A．he has felt        B．has he felt         C．he did feel          D．did he feel

So difficult _____ it to adjust to an English-speaking environment that he determined to learn English hard.

A. he has felt         B. has he felt         C. he did feel         D. did he feel

So difficult _____ it to adjust to an English-speaking environment that he determined to learn English hard.