Empty samples in glue/qqp
We are only wrapping the original dataset.

Maybe try to ask on the GLUE mailing list or reach out to the original authors? Tanks for the suggestion, I'll try to ask GLUE benchmark.
I'll first close the issue,  post the following up here afterwards, and reopen the issue if needed. 
```
qqp = nlp.load_dataset('glue', 'qqp')
print(qqp['train'][310121])
print(qqp['train'][362225])
```
```
{'question1': 'How can I create an Android app?', 'question2': '', 'label': 0, 'idx': 310137}
{'question1': 'How can I develop android app?', 'question2': '', 'label': 0, 'idx': 362246}
```
Notice that question 2 is empty string. 
BTW, I have checked and these two are the only naughty ones in all splits of qqp.