course/pr_1213/en/chapter7/9.md

# End-of-chapter quiz[[end-of-chapter-quiz]]

Let's test what you learned in this chapter!

### 1. Which of the following tasks can be framed as a token classification problem?

### 2. What part of the preprocessing for token classification differs from the other preprocessing pipelines?

-100 to label the special tokens.",
			explain: "That's not specific to token classification -- we always use -100 as the label for tokens we want to ignore in the loss."
		},
		{
			text: "We need to make sure to truncate or pad the labels to the same size as the inputs, when applying truncation/padding.",
			explain: "Indeed! That's not the only difference, though.",
			correct: true
		}
	]}
/>

### 3. What problem arises when we tokenize the words in a token classification problem and want to label the tokens?

-100 so they are ignored in the loss."
		},
		{
			text: "Each word can produce several tokens, so we end up with more tokens than we have labels.",
			explain: "That is the main problem, and we need to align the original labels with the tokens.",
			correct: true
		},
		{
			text: "The added tokens have no labels, so there is no problem.",
			explain: "That's incorrect; we need as many labels as we have tokens or our models will error out."
		}
	]}
/>

### 4. What does "domain adaptation" mean?

### 5. What are the labels in a masked language modeling problem?

### 6. Which of these tasks can be seen as a sequence-to-sequence problem?

### 7. What is the proper way to preprocess the data for a sequence-to-sequence problem?

inputs=... and targets=....",
			explain: "This might be an API we add in the future, but that's not possible right now."
		},
		{
			text: "The inputs and the targets both have to be preprocessed, in two separate calls to the tokenizer.",
			explain: "That is true, but incomplete. There is something you need to do to make sure the tokenizer processes both properly."
		},
		{
			text: "As usual, we just have to tokenize the inputs.",
			explain: "Not in a sequence classification problem; the targets are also texts we need to convert into numbers!"
		},
        {
			text: "The inputs have to be sent to the tokenizer, and the targets too, but under a special context manager.",
			explain: "That's correct, the tokenizer needs to be put into target mode by that context manager.",
			correct: true
		}
	]}
/>

{#if fw === 'pt'}

### 8. Why is there a specific subclass of `Trainer` for sequence-to-sequence problems?

-100",
			explain: "That's not a custom loss at all, but the way the loss is always computed."
		},
		{
			text: "Because sequence-to-sequence problems require a special evaluation loop",
			explain: "That's correct. Sequence-to-sequence models' predictions are often run using the generate() method.",
			correct: true
		},
		{
			text: "Because the targets are texts in sequence-to-sequence problems",
			explain: "The Trainer doesn't really care about that since they have been preprocessed before."
		},
        {
			text: "Because we use two models in sequence-to-sequence problems",
			explain: "We do use two models in a way, an encoder and a decoder, but they are grouped together in one model."
		}
	]}
/>

{:else}

### 9. Why is it often unnecessary to specify a loss when calling `compile()` on a Transformer model?

{/if}

### 10. When should you pretrain a new model?

### 11. Why is it easy to pretrain a language model on lots and lots of texts?

### 12. What are the main challenges when preprocessing data for a question answering task?

### 13. How is post-processing usually done in question answering?